Kim West, 51, and her son Ben Ford, 32, who live in Michigan, have been in a relationship since 2014 when they met for the first time since Ms West put her son up for adoption a week after he was born.
The couple are now in hiding after warnings from US authorities they would be forced to investigate their relationship if made aware of it by the public , according to the Mirror.
In Michigan state consensual incestual relationships between adults are a third degree felony punishable by up to 15 years in prison. Those convicted are required to sign the sex offenders register for life.
A spokeswoman for Michigan State police told the Mirror she was “not aware” of a complaint regarding to the couple.
Ms West, from Islington, became pregnant while studying in California and gave her son up for adoption aged 19, after which she returned to the UK.