why am i not like the Habsburgs?

the Habsburgs were really inbred and the last king of spain in their dynasty was all kinds of messed up because of it, right? but in the arab/muslim world it was (and still kinda is) extremely common to marry cousins or even uncles with nieces. my own family did that a lot back in the day - my grandparents were first cousins. so why aren't people in the middle east messed up like the Habsburgs?