A Wisconsin superintendent has apologised showing a viral same-sex marriage video to students, claiming that it was “biased” and not “balanced”.

As part of the Day of Silence in April, which condemns homophobic and transphobic bullying, Craig High School’s Gay-Straight alliance had selected ‘Kids React to Gay Marriage’ to be shown during assemblies.

The video, part of the long-running YouTube series Kids React, features a children between the ages of 5 and 13 reacting to footage of a same-sex wedding flashmob.

It has so far received over 15 million views on YouTube.

Superintendent Karen Schulte, of the Janesville School District, has apologised for allowing the video to be shown to students.

She told Twin Cities: “It’s part of my job to look at board policy and see if it’s being upheld.

“Once I viewed the video, I felt like it was biased to one side of the (same-sex marriage) issue

“It’s not something we would typically do. When looking at controversial issues, we need to look at both sides.

“The national website states that the purpose of the Day of Silence is to call attention to the harassment and discrimination faced by lesbian, gay, bisexual and transgender youth.

“In the School District of Janesville, the focus of the Day of Silence is also to eliminate bullying and harassment toward all students.”

The Fine Brothers, who produced the video, said on their Facebook page: “Wow. The episode is a great resource to start a conversation about both sides of the topic not to shut it down due to community outcries. This is unfortunate.”

Board member Bill Sodemann said it was an “obvious error” to show the video.

He said: “The video goes against our policies. We can’t use the schools to promote political agendas.”

“When dealing with these issues, you need to have balance and can’t promote political issues.”

Watch the video below: