The problem is you're looking for tangible proof. As with many things related to demographics, the problem isn't possible to recognize on a local scale.
One person with siblings does not paint a picture.
There's a Wikipedia article about China's gender imbalance
China's official census report from 2000 shows that there were 117 boys for every 100 girls. The sex imbalance in some rural areas is even higher, at 130 boys to 100 girls, compared to a global average of 105 or 106 boys to 100 girls. In 2021, the male-to-female ratio of China is recorded at 104.61 to 100.
And
Since prenatal sex determination became available in the mid-1980s, China has witnessed large cohorts of surplus males who were born at that time and are now of marriageable age. The estimated excess number of males was 2.3, 2.7, and 2.1 million in the years 2011, 2012, and 2013 respectively.[39] Over the next 20 years, a predicted excess of 10–20% of young men will emerge in large parts of China. These marriageable-age husbands-to-be, known as guang gun (光棍), translated as "bare branches" or "bare sticks", live in societies where marriage is considered as part of an individual's social status. Prenatal sex determination along with China's traditional preference for sons over daughters has left millions of men to compete over a limited number of brides, a phenomenon known as the marriage squeeze.
This is largely attributed to two things
- The Asian region in general prefers boys to girls. There is a large number of "missing women" (as in demographically) that likely numbers over 100 million.
- China's one-child policy
The latter is misunderstood as making extra children illegal. While this included infanticide, contraception and abortion, it could also include fines (Wikipedia One-child link)
The policy was enforced at the provincial level through contraception, abortion, and fines that were imposed based on the income of the family and other factors.
It's probable that Fat Cat's family was able to pay the fine, or were able to avoid the fine by being quiet about it. (Wikipedia One-child link)
If the family was not able to pay the "social child-raising fee", then their child would not be able to obtain a hukou, a legal registration document that was required in order to marry, attend state-funded schools, or to receive health care. Many who were unable to pay the fee never attempted to obtain their hukou for fear that the government would force extra fees upon them. Although some provinces had declared that payment of the "social child-raising fee" was not required to obtain a hukou, most provinces still required families to pay retroactive fines after registration.