Concerned mother

My son is about to turn 6 he was never dry overnight as a baby, always extremely wet compared to his other two brothers who were always dry. He never wakes to use the toilet and even though he goes to the toilet before going to bed has helped reduce the frequency in waking wet it has not completely eliminated the problem. I refuse to wake him to use the toilet as I feel he needs to be able to wake himself and are really hoping and praying that it will happen soon. My twin sister's youngest boy has the same problem and he is now 13. I are really concerned for his sake that he does grow out of this soon as he is not yet at the stage where he wants his friends or himself to do sleepovers. He continually tells me he will wake up and I try to tell him its ok that he will do it when his body is ready. He sometimes goes for about 2 weeks and I think YES he finally has out grown it but unfortunately it happens again.