Bear Grylls has shared a sweet tribute to son Marmaduke on Instagram on Monday as he marked his 19th birthday. The TV star shared a number of sweet family snaps of his second-eldest child - who dwarfed his famous father - and revealed it is the first birthday he has spent away from home. Bear admitted he 'missed' Marmaduke as he continues to travel round Asia during a four-month long trip. #beargrylls #son #height #tallboy #tallman #birthday