so every time i breed to him the foal is lethal white it has happened twice once with my mare once with a brood do i just geld him or is this a bug?

Straight from the game guide:

"Lethal White is implemented in this game. Two copies of White or Frame will result in a dead foal."

Your stallion has 1 copy of Frame. The mares you bred to him had to have also been Frame to produce foals with 2 copies of Frame aka Lethal White.

Just be sure to breed him to mares who aren't frame. :)

oh ok! thanks for the help i didnt know what was going on i only skimmed the game guide