Barbara Pijjan Lama has briefly touched the intriguing relation between Sun and Moon in a horoscope and the role it plays in the life of a native, in deciding whether parents would mutually live in harmony or if tension between them would affect the native at all. The rule is simple--look for the house(preferably lagna chart) in which Moon is situated and then look for the house in which Sun is present. If the relation is 2/12 or 6/8--then parents don't live harmoniously and child is affected by their animosity. OTOH, if any one of 4/10, 1/4, 4/7, 10/1 angles exist in a native's horoscope--it means an easy composition--parents won't affect the child adversely.
Take an example: In a family, there are four siblings. Lets call them A, B, C and D. A has Sun and Moon angle 2/12, B-1/4, C-6/8 and D-7/10--A and C suffer because of the conflict between parents. D and B don't suffer and stay happily---what is the difference?
A and C have different type of Karma.
B and D have favorable Karma.
A and C chose to resolve the negative Karma of former incarnations--they chose this 2/12 combination. Now, this squirmish of parents would look like a play to B and D and they easily forget it. A and C are more spiritual charts and they have difficult Karma related to parents--therefore they absorb more of negative energy 'off' parents and transform more and more of it, thereby dissolving total Karma. A and C have difficult/spiritual charts in this regard.
Now consider another example: In a family--there are 5 siblings--S, D, F, G and H. D, F and G have Sun in 6th, 8th and 12th houses and Moon in 1st, 2nd and 10th houses respectively. S and H have Sun and Moon in (2/12) and (6/8) respectively.
All of them have same parents, but:
S----Sun is in 2(good relationship with father)
S----Moon is in 12(Bad relationship with mother or mother is missing)
S----Sun/Moon angle--2/12--S absorbs 'negative' vibrations from parents to 'trigger' hidden Karmic guilt and then transforms it into pure Savitas. He chose to do that.
D---Sun is in 6th(adverse relationship with father)
D---Moon is in 1st house(good relationship with mother)
D----Sun/Moon angle is adverse--similar to S.
Likewise we could derive various effects for other members.
Note: These are very general indications. In every horoscopes Sun and Moon being karkas for father and mother respectively, are important, but there are many other factors which contribute in a fuller reading(note: I said 'fuller' reading)--like for father--see--Sun, lord of 9th house, aspects on ninth house, aspects on lord of ninth, Rashi lord of radix dipositor of 9th lord. Navmasa lord of Sun and see all of these from both ascendant and Chandra kundli.
Likewise for mother: See Moon and the fourth lord combinations from both Lagna and Chandra Kundli.