In astrology, the 9th house is traditionally associated with the father-in-law. The 9th house represents many things, including higher education, philosophy, long-distance travel, and in-laws (specifically the father-in-law).
To determine whether a father-in-law exists or not in a horoscope, you would need to look at the 7th house, which is associated with marriage and partnerships. If the 7th house has any planets or significant aspects indicating marriage, then it suggests the possibility of a father-in-law.
Additionally, the 9th house should be examined for any planets or aspects related to the father-in-law. If there are no planets or significant aspects in either the 7th or 9th house, it doesn't necessarily mean a person won't have a father-in-law, but it might indicate that the influence of the father-in-law in their life may not be as significant.
Astrology is a belief system and can be interpreted in various ways by different practitioners. While some people find meaning and guidance in astrology, it is essential to remember that it is not a scientifically proven method and should be approached with a critical and open mind. People's relationships with their in-laws can vary greatly and are influenced by many factors beyond astrological interpretations.