Trisomy 18 is a genetic disorder caused by a chromosomal anomaly, which occurs when a baby has three copies of the eighteenth chromosome instead of the usual two. It is a relatively rare disorder, occurring in only 1 in 5,000 live births.
In most cases, trisomy 18 is not inherited, but rather occurs as a random event during the formation of reproductive cells in either the mother or the father. It is not related to any known lifestyle or environmental factor. The mother's age at the time of conception is a factor, however, with older women being at higher risk.
Trisomy 18 is caused by an extra chromosome 18 in every cell of the body. In most cases, this extra chromosome is inherited from the mother, and is known as maternal trisomy 18. In a small number of cases, the extra chromosome is inherited from the father, and is known as paternal trisomy 18.
In conclusion, trisomy 18 can be inherited from either the mother or the father, although in most cases it is inherited from the mother. It is important to note that trisomy 18 is not associated with any known lifestyle or environmental factors, and is a purely random event.