A primary school headmaster has sent a letter to parents complaining pupils as young as eight were emulating behaviour seen on TV show Love Island.
Aled Rees said Year 4 pupils at Ysgol Gymraeg Teilo Sant had been commenting on each other's appearance and "pairing individuals together".
He told parents the show's contestants were "no role models for our children".
ITV said the show aired after the 21:00 watershed and was not aimed at primary school children.
Mr Rees said the fact a number of children had been watching the show came to light following an investigation into name-calling at the school in Llandeilo, Carmarthenshire.
Love Island is a popular reality dating show set in a Spanish villa where contestants are encouraged to "pair up" with each other in order to win a cash prize.
Mr Rees wrote in his letter: "I am of the opinion that primary school pupils aren't mature enough to watch a programme of this nature where a person's appearance is more important than their personality.
"The influence of the programme has led to pupils commenting on others' appearance and pairing individuals together as they are a good 'match'.
"I am sure that there are better ways to spend time with your children and more appropriate programmes they could be watching."
Parents were generally supportive of his position, Mr Rees said, and he defended attempting to influence what children watched at home.
"When what pupils are doing at home impacts on their behaviour at school, it is important that we at least communicate that with parents to make them aware of how pupils are behaving in school as a result," he explained.
Simone, a parent to two daughters aged eight and 10 who attend the school, said she supported Mr Rees.
"It is something we have said to the children - it is not appropriate for them to watch. It has an adult theme," she said.