Something I read about triggered the idea of genes, and I started thinking about the many instances of maverick ( or aberrant ) genes I have seen in my nursing career. The double XY though is not something you would pickup in an infant. It usually shows up in teenagers, if at all. Double XY, also called Klinefelter's syndrome, or 47, is a condition where the person has an extra X chromosome. Females are born with two X chromosomes, males are XY, so this syndrome affects males.. See my blog post.