bread fail

My grandma always said, "the whiter the bread, the sooner you're dead."

So why is it that my white bread always turns out and my whole wheat always does this funky split thing?

Ok, not a fail in the taste department, because it is delish (that's what matter most right?).  But in the looks department, yeaaaaaaaaaaah. Fail.

split top?

Please someone tell me what I'm doing wrong.

Am I not letting it raise enough in the pan?

Help me Obi Wan, You're my only hope... (mom, that's you)

This doesn't happen all the time, but a LOT--too MUCH of the time.

Chime in please if your homemade bread does this, if it doesn't or if you know how to fix this problem because I really want to get to the bottom it.

Thanks all you butchers, bakers and candle stick makers out there.  :)