This is prevalent not only in our culture and society but across a majority of all cultures. Growing up, I was told that boys don't cry, boys have to be strong or don't be a baby.
I do not attribute any blame to my parents for raising me on the notion that boys don't cry because from their vantage point, they were trying their best to raise their first boy to become a man by their definition based off of their own prior experiences. But home-life aside school-life, in hind sight, was brutal when it came to how boys carried themselves. Boys who showed signs of emotion other than courage or strength were immediately called out. It certainly was not a safe environment for emotional growth.
Looking back its quite sad because now I realize the harm that it has done me. My emotions to this day are constantly held back, bottled up inside. Any attempt to express a drop of my innermost feelings are suppressed now by a conditioned response of suppression. It has especially been challenging in my preparation of becoming a husband because I have difficulty communicating with my soon to be wife because somewhere deeply engrained in my mind is a pesky voice telling me to man up and not be overly emotional about things I feel strongly about. This however, I can tell you from first hand experience, has been very debilitating not only to me, but also to my fiancee. It creates a gap that can only be bridged by communicating, but the problem is communication. Luckily I have a fiancee who has been patient and talks to me to help me become the better version of myself day after day.
When the day comes, if my child is a boy, I hope I am able to learn from my past to break that cycle of emotional suppression and raise him to be a man of expression. And now that I think about it more, it takes a lot of strength and courage to share your emotions and isn't that what we want to raise our boys to be? Strong and courageous in all manners?