A 15-year-old child of same-sex parents has asked his local MLA to explain why he voted to block same-sex marriage.

Same-sex marriage is legal in England, Wales and Scotland, but continues to be blocked in Northern Ireland by the Democratic Unionist Party.

A majority of the Northern Irish Assembly voted in favour of equal marriage by 53 to 51  last year, but the DUP used peace process powers to block proposals for a fifth time.

The party has been accused of “abusing” petitions of concern, which were introduced to encourage power-sharing and cross-community support, to ‘veto’ marriage legislation despite clear majority support.

15-year-old Darragh Tibbs, of  County Down, uploaded a video to YouTube addressing the issue.

Tibbs explains that he is the child of a same-sex family, but that his parents are still denied the right to marry after 21 years together.

However, he discovered that his local MLA Gordon Dunne has repeatedly opposed equality on the issue – and wrote to him to ask him why.

In his letter, he says: “I am 15 years old and a constituent of yours. I live just around the corner from your office.

“You voted no in the Marriage Equality vote of last year: I want to know why. I am the child of a same-sex relationship and I can see absolutely no reason why my brother and I should be denied a secure family set-up.

“It seems perfectly reasonable to me that my parents; who have been in a stable relationship for twenty one years, who have two sons, should be supported by their own government.

“What gives you the right to take from my brother and me the right for legal protection for our family?

“I am asking you to explain why. I don’t want to receive an impersonal reply. I would like you to be transparent, to be an accountable figure, a leader of my constituency.”

But over six weeks since Mr Tibbs hand delivered his letter, Mr Dunne has still not replied.

Noting the Northern Ireland Assembly’s Code of Conduct highlights accountability, the teen added: “I hardly think hiding away from a 15 year old who just wants to be why is being an accountable figure.”

He urges others to send letters to the MLAs who voted against equality to ask why.

Though Mr Dunne has still not replied, a DUP spokesperson said:  “The party supports the traditional definition of marriage of one man and one woman, and we have voted along those lines many times.

“We don’t believe marriage should be redfined.”