how to boost back my brother's confidence?

[PimpinOG]

My brother lose more and more confidence of himself as the years go by, he's an average person who was not the most popular person when he was in high school, horrible in sports, did not have very good grades but average 3.0 or higher is good to me and he got that and many failures when asking for a girl on a date. His height is only like 5'6 but he never wanted to be average asian height One of the reason why his self esteem is because of me, I'm his twin brother and I'm quite the opposite of him almost completely, well I didn't have the best grades in high school but I'm doing way better then him in college, he might need five years to graduate while I will most likely only need four years. I'm not excel in sports but I get to play and compete with people who are currently in high school basketball team or ex high school basketball team, I was actually annoyed and surprised how many girls ask me out. (yes if you are above average looking this will happen and people who experienced this I'm sure it sounds good on paper but no -_-) and I'm 5'10. You can't say that my brother is ugly but many people describes that "he looks like a kid." Another problem is my cousin who is the same age as us, while he's not as tall or as charming but his intelligence is off the charts, already in a gifted training program when he was a kid and also do very well in sports, a Chinese who made it to the high school football team. Us two boost his confidence even lower because my mom told me that my brother told her that it's not fair that we got that he did not have. His confidence problem will take a while to resolve but what can I do to at least help him a little. Thanks in advance