Mistie Rebecca Atkinson, 32, was sentenced to four years and eight months jail in Napa County Superior Court, California last Wednesday.
Atkinson, of Lake County, California, had pleaded no contest to incest, oral copulation, lewd contact with a minor and distribution of lewd material to a minor in May, reported New York Daily News.
In a letter to the court, Atkinson claimed that their relationship was not incest, but a case of "genetic attraction", the Napa Valley Register reported.
This mother was found in a Ukiah, California motel room with the 16-year-old boy, who had recorded her giving him oral sex on his phone.
Authorities also recovered nude photos Atkinson had sent him after tracking him down through Facebook.
She had not seen him for 15 years.
The boy was living with his father at the time and was aware she was his mother.
She did not have custody rights to him.
"I don't feel like I should have the charge of incest because there is something called genetic attraction that is a very powerful (phenomenon) - that happens to 50 per cent of people becoming reunited with a long-lost relative," she wrote.
While little research has been carried out on genetic sexual attraction, some psychologists say family members who are separated for a long time could become sexually attracted to each other when they meet as adults.
Atkinson reportedly had no contact with her son until last year, when she began sending him inappropriate messages on Facebook.
"It appears she hadn't had any contact with the son for 15 years," a source told the New York Daily News.
"She contacted him late last year via Facebook and was sending him messages inappropriately."
The sexual contact began after police responded to domestic violence reports between Atkinson and her live-in boyfriend in Nice, California.
The relationship came to light when the boy's relatives reported the inappropriate Facebook messages between him and Atkinson.
Atkinson and the teen were found in a motel room in March.
Police found videos on the boy's phone from a month earlier showing Atkinson performing oral sex on the teenager and having sex with him.
Atkinson also sent nude pictures of herself to him from her phone, court documents said.
They had also talked about running away together.
Atkinson could be out in as little as two years and four months for good behaviour.
This article was first published in The New Paper.