"Next I'll need an attractive female boa as my mate," you say.
The genie looks at you, "Are you sure you don't mean male boa?"
"No, I'm going to be the male boa, right?"
"Ah, but that's not what you wished for, master. You wished to have
your genome translated into that of a boa constrictor's. While it is
true that XY is the male designator in humans and most mammals, birds
and some reptiles interpret the sexual designators in the reverse that
is to say the distinct sex chromosomes signify female for your new
form."
"I guess I missed that chapter in my school studies," you say. Then
you add, "Well then I wish I was a male boa constrictor."
"Ah, are you sure? Your Y chromosome will be lost, so if you wish to
be your former human self, you will be slightly different as I'll have
to pluck a Y chromosome off someone else."
"Hmmm?"