Sentence:  Too often a beginning bodybuilder has to do his training secretly either because his <WSD>parents</WSD> do n't want sonny-boy to `` lift all those old barbell things '' because `` you 'll stunt your growth '' or because childish taunts from his schoolmates , like `` Hey , lookit Mr. America , whaddya gonna do with all those muscles ( of which he has none at the time ) '' ? 
Meaning of the word marked with <WSD> tags:  a father or mother; one who begets or one who gives birth to or nurtures and raises a child; a relative who plays the role of guardian