Do the majority of hereditary conditions come from the mother's or father's side?

Question

My friend and I disagree about where hereditary medical conditions come from. He thinks they almost all come from his mothers side because that's what his family is like. I want to know where the majority of them come from. I think it's about 1/2 and 1/2.

Answer 1

There are some things that are passed through a specific s*x, like male pattern baldness is supposedly passed through females.  But there are other genes that are passed through males, and still others that are carried by both and can crop up if both parents have the gene.

Here's a rather extreme example:  

My cousin and his wife, who were both perfectly healthy, had the gene for a rare and deadly disorder, but it was recessive and caused them no problems.  All three of their sons got it from both, which made it dominant, and died before they reached age 12.  Apparently neither of them had any family history of the disorder because the genetics hadn't fallen into place elsewhere, but the family members were all carriers on his wife's side, and a couple of his siblings carried the gene as well.