For decades, I proudly identified as part Cherokee, based on the compelling oral history, passed down to me through several generations of my father’s family, of a distant white ancestor and his wife, a Cherokee woman.

Then last year, my 23andme results arrived, and I was forced to accept that even though I may identify with some Native American values and cultural traditions, I cannot claim to possess Native American DNA. Others have had similar experiences. Modern DNA testing has upset many assumptions about people’s ancestry and heritage.

What role do a person’s genes play in determining his or her identity? Surely, one’s genes help to shape one’s personality directly; but what about the indirect influences? One’s genes greatly shape one’s physical appearance — one’s body, face, voice, eyes, hair, and so on. To the extent one is judged by others on the basis of these outward traits, these traits can greatly influence one’s identity.

In the case of my mythical Cherokee ancestor, just the belief in her was enough to influence my sense of self. I never tried to join the tribe, and my only contact with Native American culture growing up was through the hodgepodge pastiche of traditions observed by the Boy Scouts. Still, I felt a connection to my legendary great-great-great grandmother. When I was younger, I even imagined that we might have walked the same trails, and I wondered if my Cherokee blood might explain some features, of my face or of my personality. When I discovered that the tale passed down to me had been false, I felt as though a small but precious part of my identity had been taken away from me.

Most people do not fashion a completely different self out of whole cloth, but grow into some version of the people who have been influential in their lives. When we are children, our sense of self is deeply rooted in our parents, family members, and classmates. In early adulthood we often rebel against the expectations put upon us, and try on different identities for size, trying to find the identity among the thousands of possibilities that fits us perfectly.

Many identities come ready-packaged: races, religions, languages, nationalities, political parties, sports teams, and companies. Identity lends membership in a group, and the many benefits that group membership can bring. It can also be a sort of prison, locking people into narrow roles and ways of thinking.

Ultimately, each person chooses his or her own identity. Acceptance of one’s chosen identity is not guaranteed. A person’s former tribe may label him a traitor, or his adoptive tribe may brand him an imposter. Most people seek a balance between being who they feel they truly are, and being someone who can find acceptance among others.