I suggest starting by doing the parents’ charts individually. What are these two people like, in terms of their natal blueprints? Then do the synastry and composite charts. If the parents separated or divorced, look for transits or progressions for key dates.
If you don’t have accurate birth times, it’s best to input the birth time as unknown, and to read the chart without houses. Just recognize that with a default noon birth time, the moon could move 6 degrees in either directions.
Then compare your chart with each parent. Keep going if you have siblings. Unless one is an only child, you and your parents are part of a larger family dynamic.
Within your chart as a stand-alone item, indicators of one’s parents traditionally are the sun and Venus (day birth) and the moon and Saturn (night birth.) However, modernly, the moon is the mother regardless of your birth time. Traditionally the 4th house cusp symbolizes the father; and the 10th house cusp, the mother. Note that the 4th also indicates one’s home, family name, and homeland, which traditionally went through the male line. Mom as the 10th is a turned house (7th from the 4th.) Modernly these designations are reversed. See what works for you. Siblings are a third house matter. Early childhood conditioning is a 4th house matter.
My one caution is that the moon is one’s experience of Mom, not Mom objectively. Saturn is one’s experience of Dad, not Dad objectively. Siblings may have their parental markers in different signs and houses; and the parents’ own charts may look very different.
Saturn in the 12th is supposedly a sign of an absent father. This could be anything from his abandonment of the family to simply being a workaholic who was not emotionally close to his children. Your 12th house may also indicate Mom’s experience of childbirth when you were born. It’s also a place to look for family secrets, if any.
Up to a point, you can use turned houses. For example, Dad’s money would be the 2nd from the 4th, or turned 5th house.
