The ancients said one is colored by their company - the environment has a huge effect on children.
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history
From 傅玄's 《太子少傅箴》 (Admonitions for the Crown Prince's Tutor), Western Jin dynasty: 故近朱者赤,近墨者黑;声和则响清,形正则影直 - therefore those near cinnabar turn red, those near ink turn black; if the sound is harmonious the echo is clear, if the form is upright the shadow is straight.
memory
朱 (zhū) = vermilion/cinnabar (red ink), 墨 (mò) = black ink. Picture a scribe whose hands are stained by whichever ink they grind.