It is already understood why gays and lesbians would like to come out to their parents. In this world, one of the greatest feelings that people will feel is being welcomed into a group. A sense of belonging will always make people feel better. A lot of gays and lesbians are often judged in public. They may be judged because of the way that they dress and even because of the way that they act.
The more that they are judged, the more that they would like to be accepted by people who matter to them the most. If you know that your parents are understanding, coming out will not be a problem. Some parents may even say that they already knew even before you say anything. There are also some parents who will be very angry. It will depend on you and the parents that you have.