There are many reason which lead to family tension.

1. Manglik - if the one person is manglik and other is non-manglik, then manglik person will try to dominate the other person.

2. Dominant Ascendant - if one ascendant is dominant to other, then it wil dominate the other ascendant. This also leads to family tensions.

3. Fourth House - Fourth house play a major role in providing house comforts. if fourth house is aspected by saturn, mars, rahu or ketu or lord of fourth house is seen by these planets, then tension will previal. Intensity of these tensions become more, when dasha or antar dasha of these stars takes place.

4. Firy Ascendants - Few ascendants are firy in nature. for example scorpio which represents fire, anger and destruction. Person having such ascendant do have the tendency of reflecting more anger. if both the ascendants have such firy ascendants, then the effect is nullifed, other family tensions do prevail.

5. Second House - if second house is seen/effected by rahu, ketu, saturn, sun or mars. Second house represents family matters and speaking skills of person. if this house is effected by bad planets, then the result would be tension in family matters due to ill words that the person will use and will destroy his family life.

6.Seventh lord - If the seventh lord is impacted by any of the bad planets, then the resultant would be tension in marriage life. Please note that such tensions would be in the dasha or antar dasha of such bad planets effecting sevent house or seventh lord.