PHILADELPHIA (WPVI) -- Philadelphia police have a man in custody on Wednesday night for allegedly shooting his 32-year-old son.It happened just before 6 p.m. inside a house along the 1400 block of South 31st Street in Grays Ferry.Police say the shooting stemmed from some type of argument.The victim was rushed to Penn Presbyterian Medical Center with a gunshot wound to the chest.He is listed in critical condition at this hour.-----