As you may know, the '80s pop icon - real name George O'Dowd - was born in England to Irish parents, so his episode largely centred on tracing his roots on this side of the pond.
George was brought to tears by revelations including his grandmother's years detained in an industrial school from the age of 6, as well as his great-uncle's execution during the War of Independence at Mountjoy Prison.
Part of the episode saw him singing rebel song 'Kevin Barry' with folk group Lankum at the Gravedigger's pub in Glasnevin, beside Glasnevin Cemetery.
See clips from the show, as well as the reaction on social media, below:
— BBC One (@BBCOne) July 23, 2018
What an incredibly moving story.
— Lankum (@LankumDublin) July 25, 2018
This is what u want too watch after a Celtic win boy George on bbc who do you think you are , republican famous family history was class show ðŸ'? pic.twitter.com/55Z5oBTTJ7
— spudoðŸ?‹ðŸ‡µðŸ‡· (@companerio67) July 25, 2018
— Tony Fucifano (@fucifano) July 25, 2018
That has to be the saddest #whodoyouthinkyouare I've ever watched, but also v interesting. No-one from Boy George's family got a run of luck. No one. Interesting that his family are so steeped in Irish revolutionary history, including a state funeral, which is a conferred honour.
— Fiona Kenny (@FionaKenny1) July 25, 2018
— Niall Ó Donnghaile â•ï¸? (@NiallSF) July 25, 2018
— India Willoughby (@IndiaWilloughby) July 25, 2018
I think this is one of the most amazing episodes I've ever seen.
— Lisa (@crankshaw_lisa) July 25, 2018
The Boy George programme was powerful viewing. The barbarity of the British in response to Ireland's bid for freedom was very emotional to watch. We have work still to do to deliver the Ireland those hero's fought and died for.
— An_fear_ciuin (@An_Fear_Ciuin) July 25, 2018
Boy George singing a dying rebel and Kevin Barry has made my night
— ðŸ'šColletteðŸ'› (@collette1251) July 25, 2018
Boy George there belting out Kevin Barry on BBC1.
Next up: Meatloaf singing Boys of the Old Brigade.
— Tin Man (@Paddy_Scotsman) July 25, 2018
Boy George's Who Do You Think You Are on BBC1 right now is excellent ðŸ'Œ
— Caolan Mc Aree (@Caolanmcaree) July 25, 2018
I’ve literally had 4 drinks today, come back online & there is videos of Boy George singing Kevin Barry wow was it really 4 drinks? ðŸ˜‚
— Rachel Lynch (@Rachel_Lynchx) July 25, 2018
Boy George singing rebel songs on BBC1.
2018 is full of surprises.
— Irvine No1 Club (@irvineno1csc) July 25, 2018