Are words like "heck," "freaking" and "sexual" really considered cuss words?

My 9 year old brother uses two of these words sometimes and he said "sexual" a few times but was stop at the last minute to "stop using that word" by our mom.

"Heck," my stepdad (his dad) takes slight offense to. He worries if my brother will say "hell," so he tries to not allow him to say heck if he is using it too often. Oddly enough, he considers it worse
than darn, dang, sucks, and even crap. Yes, he thinks heck is worse than crap!!!

My brother also says freaking, but usually he's told not to say that word because it means the F-word. What I don't understand is "sex," and its derivatives, being considered as bad words.

Sexual harassment, sex education (even officially labeled in some 4th and 5th grade classes), sex as in the gender. None of these terms are bad. Nor is "sexual intercourse," but of course it's technically an adult thing. Doesn't make sex a bad word. Going by that logic, "drugs" and "working full-time" would be considered profane or vulgar since only adults do those things.

In case anyone doesn't feel this is conservative enough, I'd like to add that my stepdad is quite homophobic (for religious and societal reasons) and sexist (not misogynist, there is a difference). He cracks a lot of racial jokes from time to time, but denies being racist. He even teaches those things to my brother.

Funny thing is they say EVERYTHING from fuck and shit and f*g, to ass, hell, damn, crap (this one my brother is allowed to use). Pretty much everything except c*nt and n*gg*r. My brother shared an opinion on VeggieTales and his dad got offended because he had an opinion on a "Christian show." My stepdad is pretty much a closed-minded person and almost always relies on societal norms, but he wants to be the 1% of parents that are highly egomaniac'd and bigoted.
Vote A
Vote B
Open poll :)
Vote C
Select age and gender to cast your vote:
Are words like "heck," "freaking" and "sexual" really considered cuss words?
Add Opinion