▁his ▁brothers ▁Carl ▁( El li ott ▁T itt ensor ) ▁and ▁Ian ▁( G er ard ▁K ear ns ). ▁Through out ▁the ▁series , ▁Li am ▁is ▁pract ically ▁raised ▁by ▁his ▁older ▁sister s , ▁F iona ▁( An ne - Marie ▁D uff ) ▁and ▁Deb bie ▁( R eb e cca ▁Ryan ), ▁as ▁his ▁father ▁Frank ▁( David ▁Th rel fall ) ▁is ▁lazy ▁and ▁mother ▁Mon ica ▁( An n abel le ▁A ps ion ) ▁in e pt - ▁when ▁she ▁is ▁around . ▁In ▁later ▁episodes , ▁Li am ▁shows ▁considerable ▁intelligence ▁and ▁resource ful ness ▁like ▁sister ▁Deb bie ▁and ▁is ▁also ▁an ▁out sp oken ▁at he ist . ▁In ▁series ▁ 5 , ▁signs ▁of ▁genius ▁in ▁Li am ▁became ▁obvious ▁when ▁he ▁was ▁shown ▁to ▁be ▁an ▁ade pt ▁car ▁th ief , ▁much ▁like ▁Steve ▁Mc B ride ▁( James ▁Mc A voy ), ▁and ▁was ▁seen ▁later ▁to ▁use ▁a ▁def ibr ill ator ▁on ▁a ▁com at ose ▁Frank ▁when ▁it ▁was ▁thought ▁that ▁his ▁heart ▁had ▁stopped . ▁In ▁series ▁ 6 , ▁it ▁is ▁revealed ▁that ▁Li am ▁is ▁a ▁tal ented ▁music ian , ▁and ▁also ▁fl uent ▁in ▁Sign ▁Language . ▁Given ▁his ▁academic ▁performance , ▁the ▁school ▁determ ines ▁Li am ▁to ▁be ▁an ▁exception ally ▁gift ed ▁pup il , ▁which ▁leads ▁to ▁him ▁being ▁awarded ▁a ▁special ▁scholar ship . ▁During ▁an ▁interview ▁at ▁a ▁local ▁university , ▁he ▁initially