Cel­lu­lar sleuthing

Us­ing DNA to test con­jec­tures about your fam­ily his­tory.

Canada's History - - ROOTS - Paul Jones, a former pub­lisher, is a writer, a con­sul­tant, and an avid ge­nealog­i­cal re­searcher and vol­un­teer. Note: Some names have been changed at the re­quest of those who have gen­er­ously al­lowed their sto­ries to be told.

My friend El­iz­a­beth, an adoptee, had good rea­son to be­lieve that her bi­o­log­i­cal fa­ther was Leslie Elm­wood, an English­man who had died in the 1990s. In­for­ma­tion about his life cor­re­sponded in ev­ery way to the snip­pets of truth, halftruths, and faded mem­ory El­iz­a­beth had gleaned from Ivy, her tac­i­turn bi­o­log­i­cal mother. A dec­o­rated nurs­ing of­fi­cer, Ivy served in the renowned Burma Cam­paign dur­ing the lat­ter years of the Sec­ond World War. That’s where El­iz­a­beth had been con­ceived in 1945.

How­ever, shortly after au­to­so­mal DNA test­ing first be­came af­ford­ably avail­able to the gen­eral public about seven years ago, El­iz­a­beth quickly es­tab­lished that she bore no ge­netic re­la­tion­ship to Leslie’s sur­viv­ing brother. In an ear­lier era, El­iz­a­beth might have con­tin­ued in­def­i­nitely in the mis­taken be­lief that Leslie Elm­wood was her bi­o­log­i­cal fa­ther. It’s no won­der that rel­e­vant ge­netic ev­i­dence is now ex­pected to be part of any ge­nealog­i­cal re­search project wor­thy of the name.

Au­to­so­mal DNA (atDNA) is the ge­netic ma­te­rial con­tained in your twenty-two non-sex chro­mo­somes (that is, ex­clud­ing the X and Y chro­mo­somes). You in­herit fifty per cent of atDNA from each par­ent, but, due to the ran­dom­ness of re­com­bi­na­tion in sub­se­quent gen­er­a­tions, you re­ceive only an av­er­age of twenty-five per cent from each grand­par­ent, 12.5 per cent from each great-grand­par­ent, and so forth. Test­ing com­pa­nies ex­am­ine hun­dreds of thou­sands of lo­ca­tions on these twenty-two chro­mo­somes in or­der to com­pare your DNA with that of oth­ers who have been tested. When a match be­tween two peo­ple is found, sta­tis­ti­cal al­go­rithms cal­cu­late the likely de­gree of re­la­tion­ship, such as full sib­ling, aunt or un­cle, or sec­ond cousin.

On av­er­age, a pu­ta­tive un­cle (such as Leslie’s brother) and niece (El­iz­a­beth)

should ex­pect to share twenty-five per cent of their atDNA. The ab­sence of any ge­netic re­la­tion­ship what­so­ever cast grave doubts on the hy­poth­e­sis that El­iz­a­beth was the bi­o­log­i­cal daugh­ter of Leslie. Don’t cry for El­iz­a­beth, though. The telling of her story has barely be­gun.

There are two uses for DNA tests: to as­sess ex­ist­ing hy­pothe­ses and to gather in­for­ma­tion that may gen­er­ate fresh hy­pothe­ses. El­iz­a­beth’s use of atDNA to con­firm or deny her pa­ter­nity was an ex­am­ple of hy­poth­e­sis­check­ing in that she com­pared the DNA of peo­ple con­jec­tured to be ge­net­i­cally re­lated. If they had matched, the hy­poth­e­sis would have gained cred­i­bil­ity. When they didn’t match, El­iz­a­beth needed a new hy­poth­e­sis in her quest for her bi­o­log­i­cal fa­ther.

Let’s take a look at fur­ther ex­am­ples of hy­poth­e­sis-test­ing with atDNA.

Con­sider my friend Joy and her mys­te­ri­ous grand­fa­ther Moses Levine. He died in Al­berta in the 1940s, but his ori­gins were al­ways un­clear. Fam­ily lore and cred­i­ble records both af­firmed that, as a young man in the 1880s, he had made his home in the Dakota Ter­ri­tory of the United States. U.S. cen­suses of the time iden­ti­fied him as hav­ing French-Cana­dian her­itage, but no record of him as a child or youth could be found in Cana­dian cen­suses or in Que­bec parish records.

The break­through came when a young Moses Lavine of French-Cana­dian parent­age was lo­cated in the 1870 and 1880 U.S. cen­suses — a res­i­dent of up­state New York, liv­ing just a few kilo­me­tres from the Cana­dian bor­der. This New York Moses dis­ap­peared from the doc­u­men­tary record after 1880, just in time for the ap­pear­ance of Dakota Moses. Were they the same per­son?

Au­to­so­mal DNA test­ing to the res­cue! In Joy we had a di­rect de­scen­dant of Dakota Moses. If we could find a liv­ing per­son known to be ge­net­i­cally re­lated to New York Moses, we could then use atDNA test­ing to see if there was any bi­o­log­i­cal con­nec­tion be­tween the two lines. After sev­eral false starts, we even­tu­ally iden­ti­fied Glo­ria, a liv­ing great-grand­daugh­ter of the youngest sis­ter of New York Moses. For­tu­nately, Glo­ria set aside her mis­giv­ings and agreed to take an atDNA test. After a sus­pense-filled wait for the find­ings, the test­ing com­pany re­vealed that Glo­ria and Joy share DNA in an amount ex­pected of sec­ond or third cousins. Bull’s eye! Ac­cord­ing to our con­jec­tured fam­ily tree, Glo­ria and Joy are in fact sec­ond cousins once re­moved, ge­net­i­cally half­way be­tween sec­ond and third cousins.

Con­trary to pop­u­lar be­lief, DNA re­sults do not pro­vide ab­so­lute proof of our hy­pothe­ses. In El­iz­a­beth’s case, there was an­other pos­si­ble, al­beit im­prob­a­ble, ex­pla­na­tion for the find­ing — an un­known adop­tion of ei­ther Leslie or his brother. In Joy’s case, per­haps New York Moses and Dakota Moses were sim­ply first cousins and not the same per­son. Or maybe, un­be­knownst to Joy and to Glo­ria, they share a fam­ily con­nec­tion on an­other line en­tirely. That would be quite a co­in­ci­dence, but stranger things have hap­pened.

Do we se­ri­ously be­lieve such al­ter­nate hy­pothe­ses? No. The philo­soph­i­cal prin­ci­ple of Oc­cam’s ra­zor tells us to favour the sim­plest ex­pla­na­tions, and the doc­u­men­tary record pro­vides no sup­port for hy­pothe­ses other than the front-run­ners. But if new ev­i­dence were to emerge, DNA find­ings could be ex­plained in dif­fer­ent ways. This is why DNA anal­y­sis sup­ple­ments but does not re­place the tra­di­tional con­tents of the ge­neal­o­gist’s tool kit.

So how did El­iz­a­beth find her real birth fa­ther? It’s a story that de­serves a book, not a cou­ple of hun­dred words. Here’s the gist: Notic­ing that she — un­like her ma­ter­nal half-sib­lings — had a large num­ber of atDNA matches from the south­ern U.S., El­iz­a­beth hy­poth­e­sized that her bi­o­log­i­cal fa­ther had a ge­netic con­nec­tion to the area. She compiled a can­di­date data­base of roughly three hun­dred Amer­i­can ser­vice­men, mostly pi­lots and am­bu­lance driv­ers, whose sta­tion­ing in the spring of 1945 might have brought them into con­tact with her mother. El­iz­a­beth re­searched and con­structed fam­ily trees for sev­eral dozen of the men who seemed most likely to have met her mother — es­pe­cially men from the Ame­rian South. At the same time, she compiled a sur­name list from the sup­plied fam­ily trees of her atDNA matches, in par­tic­u­lar those names that seemed to be from her pa­ter­nal side. El­iz­a­beth then com­pared the an­ces­tral sur­names of each can­di­date ser­vice­man with the sur­names on the list. After un­told hours of work, El­iz­a­beth iden­ti­fied a U.S. pi­lot who had sur­names on both his pa­ter­nal and ma­ter­nal sides that cor­re­sponded to names on El­iz­a­beth’s list.

Re­gret­tably, this man had died in the 1990s, but two daugh­ters were alive and well in Florida. To set­tle the mat­ter be­yond any rea­son­able doubt, El­iz­a­beth per­suaded the daugh­ters to un­dergo atDNA test­ing. Both were as­sessed to be half-sib­lings to El­iz­a­beth. Game, set, and match!

Most DNA projects are not this com­pli­cated. (If they were, ge­netic ge­neal­ogy would not be as pop­u­lar as it has be­come.) Yet it’s not sim­ply a mat­ter, as many seem to think, of do­ing the test and re­ceiv­ing a re­port with your an­ces­try back to the Mid­dle Ages. Yes, you do get a re­port, but in­ter­pret­ing and us­ing it re­quire knowl­edge and ef­fort. That’s what we’ll look at next time. We’ll con­sider the chal­lenges faced by peo­ple with­out spe­cific hy­pothe­ses to test but who are cu­ri­ous about what atDNA can say about their an­ces­try. How do you use that daunt­ing re­port to gen­er­ate fresh in­for­ma­tion and hy­pothe­ses about your her­itage?

El­iz­a­beth re­searched and con­structed fam­ily trees for sev­eral dozen of the men who seemed most likely to have met her mother.

The chart shows schemat­i­cally how au­to­so­mal DNA is in­her­ited over suc­ces­sive gen­er­a­tions.

Newspapers in English

Newspapers from Canada

© PressReader. All rights reserved.