Type 2 is highly heritable. It is seen nine times more frequently in male offspring of male alcoholics and I don't have any doubt this will extrapolate into sexual compulsivity. It is seen four times more frequently in female offspring of female alcoholics.
It usually begins before 25 years of age but we can also see it in older and geriatric populations.
Jim (AABB p.35) didn't start drinking until he was 34 but, within a short period, he was so violent that he had to be put into an asylum - an inebriate asylum. In those days they used the word inebriety - inebriety to alcohol, inebriety to cocaine, inebriety to morphine, inebriety to sex - and they had asylums. They also had homes to which Jim would have been relegated once he got out of the asylum. Jim didn't start drinking until he was 34 but he's a Type 2.
I once treated a 70 year old nun who had always taken sacramental wine but, in retirement, had begun drinking a glass of wine at night to help her sleep. Within six months, she was drinking all the wine she could get her hands on. Because of her situation, she had not been exposed to alcohol, drugs or other things, until she reached 70. Then she exploded - like Jim.