Sigh. It's a very common misconception that the term "mother fucker" (two words, not one) denigrates a man who has sex with his own mother. Fuck Wikipedia, and fuck the ignorant idiots who spin whole fictions, and especially fuck the lazy dipshit readers who just assume that WP is correct, because it's easier than following up with their own research. Yeah, you heard me--Jimmy Wales can suck a fattie, while we're at it.
In reality, the term "mother fucker" refers to a man who has sex with SOMEONE ELSE'S MOTHER, specifically with a woman in some kind of tight spot (e.g., economically) who agrees to sex with that man only out of desperation. The woman doesn't really want to sleep with this man, and she isn't a prostitute in the professional sense, but this man presents an alternative to watching her children go hungry.
The term gained tremendous traction during WWII, originally amongst black American GIs, and was applied literally to American soldiers (black, white, or otherwise) in war-torn Europe who would trade food, money, or anything of value (cigarettes, chocolate, booze) for sex with desperately poor or starving French and German women. Many of these women were home-makers whose husbands had been conscripted away, killed, or imprisoned, leaving the women to support the couple's children alone. Many lacked trade skills, and the war damaged the local economies so badly that they had few, if any, alternatives.
So calling a man a "mother fucker" meant that he was A) taking advantage of poor and downtrodden people with no options, and B) incapable of seducing non-desperate women. Anyone with experience growing up in desperate poverty, or who saw his own parents humiliated by circumstances beyond his control, would probably consider that kind of behavior to be a pretty low thing.
In the last sixty or so years, the term has entered the popular slang as a term of derision ("That Richard Nixon is a real mother fucker, you know?"). More recently, it's been used as an indicator of extraordinary intensity, not necessarily in a derisive sense, but usually still carrying some implications of harshness ("I fell asleep out in my lawn chair, yesterday, and got a mother fucker of a sunburn.") or intimidating awesomeness ("That Shaft, he's one baaaad mother fucker.").
Do your part--fight the ignorance!