This relationship could have become serious fast, because you relate closely to your lover and you strongly identify with their family and past on an emotional level. The natural intimacy between you makes you really comfortable with this person from the start, and if you meet their parents or siblings, or even their best friends, you feel an immediate affinity for them and vice versa, as if you're the missing piece of the group! It's likely that you feel immediately accepted into your lover's inner circle; if you encounter any problems of resistance from family or friends to the relationship, it is probably just token opposition and quickly fades away.
You're emotionally sensitive to them as well, knowing just what they need to feel secure and well-loved, and it is rare that you will hurt their feelings. Needless to say, this kind of aspect definitely supports a lot of love and understanding between you that translates well to the long-term! If you have made or plan to make a commitment to this person, you can expect that their family and close friends are an integral part of your relationship. Starting your own family together isn't out of the question, if things move in that direction.