There is a huge community of converts in Arizona. In the 1970s and 1980s some guy named Yogi Bhajan converted lots of white people. The only thing that separates these converts from people born into the religion is that converts place a huge emphasis on yoga.
There are alto of whites that converted to Sikhism, many live out in western USA. But a problem is that Indians Sikhs do not accept non Indian Sikhs usually. That is why you will find white Sikh temples and Indian Sikh temples.