Just for the record lol - I have no idea what is discussion about X and Y and who thinks what but there is some confusion so let me just give facts :
Mom's eggs have X chromosomes (among many other ones , of course)
Dad's sperm cells have EITHER an "Y" OR an "X" chromosome

When Dad's "Y sperm" come to Mom's "X egg" - we get a baby boy that has XY set of chromosomes in allll of his cells in the body.

When Dad's "X sperm" cell fusses with Mom's "X egg" - we get a baby girl with XX set of sex chromosomes in allll of her cells in the body.