Is it true that men's sexual attraction to female breasts is just because culture/media sexualized it?

Yes, it seems that the body parts that get hidden the most, get men fantasizing about them.  Back in the Victorian times when women were dressed in up to the kneck and down to the ankles dresses, men had knee and elbow fetishes.  Then as hems shortened and necklines plummeted, with a hint of cleavage, boobs became the body part to obsess over.  Bums and Boobs are pleasantly rounded and everyone likes a well rounded shape!

You are correct in a question of culture and media sexualizing breasts...

But it's much deeper than that!  By natural selection different cultures have altered the appearance of the human breast in different forms! How powerful is that!

By that natural selection process the alteration of the human breast has been around for Millions of years before any media arrived to  capitalize on them! 

All that attention and resulting natural selection ... in all probability... came around very rapidly after man gained the ability to walk upright on two feet! (allowing them to be more fully displayed!)

Doesn't make you feel any better about all the attention ... does it?

Given that breasts aren't considered sexual in many world cultures this is likely a learned trait. 

I don't know, but there are other cultures where they weren't considered sexual. It might be biological but culture can turn it *off*.

"So is it true that it is just because of culture and hiding them?"

Kind of. There are cultures out there where women walk around with no top on and nobody bats an eye. The men do still find breasts attractive but its different from how we see them. You know how some men like legs, backs, feet etc? That's more how other cultures see breasts. Still sexy but not at the same level as breasts. 

The only reason why you even have chesticles to begin with is because men over the course of hundreds of thousands of years selected women with full breasts. If not for men you would have orangutan titties. So no, I don't think it's just cultural. I think men like breasts because they have always liked breasts. A firm breast tells a man a woman is ovulating and ready for his ****. The same reason why you wear makeup like blush. It's not because it makes you feel pretty (durrr!) it's because it makes you appear as though you are ovulating. You want ape man to wreck your cervix and this charade pretending it's about anything else is really stupid.

"Is it true that men's sexual attraction to female breasts is just because culture/media sexualized it?"

No, it's false.  Most human behaviour is ingrained by design, either creation or evolution, whatever your fancy. The idea that most  human gendered behaviours are socially constructed is a feminist construction in and of itself ... never proven, only theorized.

When I was10 years old, I pulled out a large frozen fish to scare my cat with.  This fish was easily twice the size of the cat.  Instead of being afraid, her eyes lit up and she meowed incessantly realizing that not only was it not scary .. but that it was food.  This was a house cat that had never seen a fish before in her life, yet she instinctually knew that this huge thing was her prey.  Just like men know women's breasts to be sexual organs to them, and they are driven into a sexual response.

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The attraction to breast has been heightened, imagined by culture. Just like now those fat asses that were once disgusting, have no become desirable big butts. Look around at the world and you'll see slight emphasis on this part of that.

@Anonymous: Women even in most of those cultures don't common walk around topless. It's commonly argued that the allure of breasts is lower in those cultures, but there is no real evidence to support it. 

Answer: 

Women admit they like a mans chest all the time. I doubt you will find a straight woman easily that isn't attracted to a fit mans chest. 

Anyway, you can't very well create sexual attractions through culture. You can create more allure to a body part perhaps through culture, but that's it.

And one other thing, men are attracted to the entire body of a woman. The allure is so high that societies got in their head that covering women up might help control it. Does it? Nope.