A mother and son have pleaded guilty to incest after "falling in love”.

Monica Mares and her son Caleb Peterson were arrested last year after an argument with a neighbour led to the police being alerted to their relationship.

The pair accepted a plea deal and will avoid jail, but have to stay away from each other until 2018, reports MailOnline.

Mares met Peterson for the first time in 18 years after he was given up for adoption as a baby. They got in contact via Facebook towards the end of 2015, before the 37-year-old picked up her son from his adoptive father’s home in Texas.

The pair quickly developed romantic feelings, before the relationship became sexual a few weeks later.

“It felt like I met somebody new in my life and I fell in love with him,” she told MailOnline in 2016.

She continued: "At first I told him, 'I'm sorry I don't know how you are going to react to this. I'm your mom and you're my son, but I'm falling in love with you'."

She said she had been attacked outside her home and subjected to death threats after locals in her town of Clovis, New Mexico, heard the news.

But if told to choose between her other nine children and Peterson, “I’d choose him,” she said.

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In a separate interview, Peterson told the website he started falling in love with his mother about a week after meeting her. “It went beyond a mother-son relationship, I never really viewed her as my mum,” he said.

The first time he kissed her, “we were hanging out just talking and I looked at her and she looked at me and I kissed her”.

“It was a real kiss, it had feelings behind it, there was a spark that ever since then it just stayed.”

The 20-year-old argued they were both “consenting adults”.

In August the pair went public with their story to raise awareness of Genetic Sexual Attraction (GSA) – sexual attraction between close relatives who first meet as adults.

The term was coined in the 1980s by Barbara Gonyo, founder of Truth Seekers in Adoption, a support group for adoptees and their new found relatives.