Dad's Diet Before Conception Affects Kids' Health

Was is meant with high fat diet? Combined carbs and fats like in donuts? Ketogenic/low carb high fat diet?

Makes sense to me. This is completely a layman's imagination talking, but I've always thought of a man's sperm as the "current state of the man". A man produces sperm constantly and with what we know of epigenetics, he can live his life for better or worse. For instance, exercise, vitamin D levels, and alcohol use all result in changes to his epigenetic expression.

Contrast this with a woman, whom is born with all the eggs she will ever have. She doesn't produce any new ones and thus her "job" is to maintain the freshness of her eggs for as long as possible. It also makes sense that youth is the best time for her to conceive a child as her eggs will not have accumulated as much damage as an older woman.

This kind of paints the picture that a man who is taking care of himself should aim for a young woman so as to give their children the best genetic roll of the dice.