The number of combust planets in a chart actually shows the absence of father or father figure or his guidance in life. Remember that a planet gets combust because of Sun's heat and fire. Sun represents Father, so a combust planet shows that father or his guidance was never present in person's early life to learn things related to that planet.

Like, if Venus is combust then may be parents themselves were in a bad relationship and person didn't any good guidance from father on how to deal with relations.

If Mercury is combust then father was absent to guide person about how to deal with siblings or improve skills.

If Moon is combust then father may lack emotional touch which may make person detached or unemotional.

If Mars is combust then father didn't guide how to face the adversities in life with courage and that made person timid.

If Jupiter is combust then father was not there to plant good morals or values in child.

If Saturn is combust then father was not there to guide his child about right duties or career in life.

Now, it is not that this scene will remain for whole life. As father is absent to guide on these matters in early life, person will learn these lessons through life experiences and that's why a combust planet gives much better result in person's 30s. Till then, it is learning phase.

A very good question can be that Father is same person for all his children then why different children have different planets combust?

Excellent question and here are the main reasons I feel -

1. Father is same but children are different. As they are different children, majority of times they will receive different behavior from their parent. For example, I always felt that parents have more trust on the eldest child rather than youngest child. Youngest child is mostly treated as not so intelligent and sometimes even childish throughout life. So, what parents are doing unknowingly? They are boosting the confidence of the eldest child but they are not helping the confidence of younger child a bit.

2. Then different children may have different capabilities or weaknesses. As a parent, Father may focus on X area of life for a child and can neglect Y area of life but for another child he may focus on Y area of life and may neglect X. So in this example, although he is present in life but due to different requirements of children he is focusing/ignoring different areas of life.

3. Now Astrologically, suppose out of 2 children one has Venus Combust and other has Mercury combust. So, by karaka representations it looks like different areas of life got combust but what if Mercury is darakaraka of 2nd child or Mercury rules 7th house of 2nd child. It makes the same case that relationships are combust for both children. So, charts need to be read in entirety.

4. Then a lot depends on the karma we are carrying from past lives with that person who is now father in this life. If my karma with my father is related to power struggle then may be my career or authority related planets will be combust and if my karma with my father is related with relationship then my relationship oriented planets may be combust.

So, these are few reasons how different planets of different children of same parents can get combust. As I said, these are only few reasons. There can be many other reasons too. Again, nothing is generic and applicable on all parents. Hence, overall chart reading is necessary.

Thanks,

SPB