The crucial part of that world is the home where parents relate to children.
( ( ( The ( crucial part ) ) ( of ( that world ) ) ) ( ( is ( ( the home ) ( where ( parents ( relate ( to children ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ crucial) (NN part)) (PP (IN of) (NP (DT that) (NN world)))) (VP (VBZ is) (NP (NP (DT the) (NN home)) (SBAR (WHADVP (WRB where)) (S (NP (NNS parents)) (VP (VBP relate) (PP (TO to) (NP (NNS children)))))))) (. .)))
The crucial part is that parents relate to their own children only.
( ( The ( crucial part ) ) ( ( is ( that ( parents ( ( relate ( to ( their ( own children ) ) ) ) only ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ crucial) (NN part)) (VP (VBZ is) (SBAR (IN that) (S (NP (NNS parents)) (VP (VBP relate) (PP (TO to) (NP (PRP$ their) (JJ own) (NNS children))) (ADVP (RB only)))))) (. .)))