Sometimes boys will experience breast growth during puberty that resembles the type of breast development seen in adolescent girls. This condition, known as gynecomastia, isn’t harmful and is actually relatively common. Around two-thirds of boys develop temporarily enlarged, tender breasts, usually around age 13 or 14. It happens because during puberty boys experience a surge in estrogen, which is always produced in males but generally only in small amounts.
For 95% of affected boys, the problem will go away within six months. If it doesn’t, consult your doctor. There are prescriptions that can be taken which will counteract this estrogen surge and fix the problem.
The biggest issue tends to be that the condition can be embarrassing, especially if a child is teased about it by their peers. Help them understand that it’s a normal part of puberty and is in no way indicative of their masculinity or femininity.