Patient's question:
I and my boyfriend have the same maternal grandfather, but different maternal grandmothers. He is the son of my aunt. In other words, his mother and my mother are siblings with the same father but different mothers.Doctor's answer:
Analysis of the Condition: Hello! It is not permissible for you to marry each other. You are prohibited from marrying within three generations of close relatives.Guidance: Marriages between close relatives have a high mortality rate in offspring and often result in intellectual disabilities, (deformed children), and genetic diseases. This is because couples who marry closely share more identical genes from common ancestors, making it easier for harmful recessive genes that are detrimental to survival to combine (i.e., become homozygous) in the offspring, thus increasing the likelihood of giving birth to children with poor quality. In contrast, when non-close relatives marry, the couple has no blood relationship, and they share very few identical genes. The recessive harmful genes they carry are different, making it less likely to form homozygous recessive harmful genes (patients). However, in close marriages, the couple is highly likely to carry the same recessive harmful genes, making it easier for them to meet in the offspring, thereby increasing the incidence of genetic diseases.
The following table lists several recessive genetic diseases, showing that the incidence rate in offspring of close marriages is several times higher than in offspring of non-close marriages. Additionally, polygenic genetic diseases such as hypertension, schizophrenia, congenital heart disease, anencephaly, and epilepsy also have significantly higher incidence rates in children born to close relatives compared to those born to non-close relatives.