Um, no, it's isn't natural. Breasts aren't inherently sexual. They're sacks of fat for feeding babies. They have no sexual purpose whatsoever. They're only sexualized because of social conditioning. Women in Africa are topless all the time and aren't sexualized because those people aren't socially conditioned to sexualize breasts. And I don't even have to be topless for men to objectify me. I can be wearing a -blam!-ing parka and men will still make gross comments. It's a culture of male dominance and entitlement, it has nothing to do with how we're dressed.