Gynecomastia defines breast development during puberty in males. It happens in about 1/3 of all males during puberty and is normal! It should go away in a year or two, but if it doesn’t you can talk with your doc.

If you’re beyond puberty then it’s possible that you’ve developed breasts for another reason. Carrying excess weight can certainly cause weight gain as can marijuana use. It can be natural for breasts and breast tissue to produce discharge, so that’s nothing concerning. Marijuana can also cause nipple discharge. Just FYI.