WILL HAVING MY GENOME SEQUENCED AFFECT MY FAMILY MEMBERS?
As noted above, given that half one’s DNA comes from one’s mother and half from one’s father, one’s genome information will indirectly reveal some, but not all, of the genome information of one’s parents. Similarly, one half of one’s DNA is shared with one’s siblings (on average) and biological children (exactly), but it is not known which half. Thus, one’s genome sequence may suggest things to watch out for in siblings and children, but nothing guarantees that they share one’s disease risk mutations. An exception is identical twins, who share the same DNA (except for a small number of de novo and somatic mutations), so that the sequencing of one twin will reveal the genetic risk of the other. Along the same line, cousins will share one- eighth of their DNA and will share some of the same mutations, but not as many as they share with siblings or children. Thus, cousins may share some of the same risks, but because they have even less shared DNA, their risk will be different. Generally, when one family member is sequenced, he or she may want to discuss with other close family members (especially parents, siblings, and children) whether they want to know the results and whether follow-up tests should be performed. If the individual plans to release the data to the public, it would be useful to discuss this with other family members as well.