Neil Patrick Harris gave his twins a "biology" lesson to mark Thanksgiving (26.11.15).

Neil Patrick Harris' twins (Instagram)

Neil Patrick Harris' twins (Instagram)

The 42-year-old actor - who has a five-year-old son, Gideon Scott, and a daughter, Harper Grace, with his husband David Burtka - cooked up a spectacular feast to mark the annual celebration and also posted a photograph of his children holding misshapen carrots while dressed in their pajamas.

Writing on his Instagram account, Neil joked: "Earlier today, prepping for Thanksgiving dinner. Teaching our children both cooking and apparently, biology. #thankful"

The former 'How I Met Your Mother' star - who revealed he is gay in 2006 and had his children via a surrogate mother - also posted an image of the delicious-looking food he'd prepared for the big day.

He captioned the image: "Happy Thanksgiving everyone! I'm so thankful for food, family, friends, and [David]. Loving today (and turkey)!"

Neil also gave fans a further insight into his personal life by broadcasting his family's dinner via the video streaming app Periscope.

Earlier this year, Neil admitted he comes across as the "bad cop" when he disciplines his children.

However, he added: "With kids you need to be able to answer their questions in earnest and you need to try and get from the way they are asking the question to what they might actually be wanting to know.

"The more communicative they have become, the sweeter it's been for me."