I have two sons, one 3 1/2 year old who was born with a partial extra thumb (with bone) on one hand, the other son, 2 1/2 weeks was also born with the same condition. Neither my family nor my husband's have any history of polydactyly so we were surprised to learn with our recent son that it is a genetic thing instead of a fluke (as we were told with the first son since there was no family history). My oldest son had his extra thumb surgically removed when he was 16 months and it looks almost good as new. He has full function of it (the Dr. cautioned us about the possibility of limited function and/or arthritis) and he hasn't complained of any arthritic pain. I woul not worry too much about it at this point if the child is born healthy in all other respects. For your own peace of mind however, make an appointment after about a month or so following the birth with a hand surgeon to have x-rays performed and to learn more about what is involved in having them removed.