DrPete is absolutely right. You should be weight bearing predominantly through your ischial tuberosities/sit bones, with some light pressure on your pubic ramus, and slightly more in an aero position. If you are sitting further back, you are sitting on your sacrum or coccyx (which a lot of people do). This can cause injuries from sacrotuberous sprain to muscle straings to nerve root impingement, and so on.

If you're riding further forward, your pelvis is tilted likely more anteriorly or forward, and you are sitting on your perineum, and resting on the ischiopubic rami, and the internal portion of genitalia. NOT a place which was designed to bear weight. This area is surrounded by nerves and arteries.

If I ride that far forward, it just squishes my girl parts... which kust sucks. If you're a man and you're bearing weight in this area, you're also squishing erectile tissue and your urethra.

tata