Ginny’s Ge­nealog­i­cal Gems

DNA as a tool for Re­search

Serve Daily - - NEWS - By Ginny Ack­er­son

There is a grow­ing in­ter­est in DNA as a tool for ge­nealog­i­cal re­search. Un­der­stand­ing your genes may help you fur­ther your fam­ily his­tory and open sev­eral ar­eas of in­ves­ti­ga­tion.

DNA re­search is based on the fact that ev­ery hu­man be­ing is born with 46 chro­mo­somes. Gen­der is de­ter­mined by chro­mo­somes con­sist­ing of an X from the mother and ei­ther an X or Y from the fa­ther. If a child has an X from the fa­ther, she is fe­male and if they re­ceive a Y the child is male.

In­for­ma­tion in the Y chro­mo­some (Ycs) passes mostly un­changed from fa­ther to son for gen­er­a­tions. Anal­y­sis of this ge­netic in­for­ma­tion in liv­ing peo­ple can help you de­ter­mine whether you share a common pa­ter­nal ances­tor with another liv­ing per­son. Based on the num­ber of ge­netic mark­ers shared with another per­son, you can es­ti­mate how many gen­er­a­tions in the past your common pa­ter­nal ances­tor lived. Ycs test­ing can help in ver­i­fy­ing a common pa­ter­nal ances­tor, or learn about the ori­gin of a par­tic­u­lar sur­name. While only males carry the Ycs, a woman can have a male rel­a­tive tested on her be­half to ob­tain this in­for­ma­tion.

In ad­di­tion, each hu­man be­ing car­ries a ge­netic mol­e­cule in their cells called the mi­to­chon­drial DNA (mtDNA). This ge­netic com­po­nent is found in the mi­to­chon­dria, and is in­her­ited ex­clu­sively along the mother’s side. Both males and fe­males carry mtDNA, but only women pass their mtDNA to their chil­dren. MtDNA is help­ful in ver­i­fy­ing the ex­is­tence of a common ma­ter­nal ances­tor or to study the an­cient ori­gins of our ma­ter­nal line.

A third op­tion is au­to­so­mal DNA which is shuf­fled at each gen­er­a­tion and only half of it is passed to our off­spring. It does not follow a di­rect path of in­her­i­tance as does the Ycs and mtDNA de­scribed above. How­ever, cur­rent test­ing pro­vides a survey of one mil­lion or more sites on a per­son’s nu­clear genome. This in­for­ma­tion is help­ful in iden­ti­fy­ing re­cent cousins within the last five gen­er­a­tions, or the eth­nic ori­gins of your fam­ily tree. Com­pa­nies like 23andMe, Fam­ily Tree DNA, and An­ces­try all of­fer au­to­so­mal test­ing for ge­nealog­i­cal pur­poses. Each company of­fer­ing th­ese tests has tu­to­ri­als on their web­site to help with the in­ter­pre­ta­tion of your re­sults. Though th­ese DNA tests do not pro­vide you with a de­fin­i­tive pedi­gree, they do give spe­cific di­rec­tion to your re­search and con­tact in­for­ma­tion for liv­ing rel­a­tives.

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