Yin Yang

This collage of twin grandsons at 3 1/2 months old needs a caption! They are very different in personalities! 

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In Chinese philosophy, yin and yang is a concept of dualism in ancient Chinese philosophy, describing how seemingly opposite or contrary forces may actually be complementary, interconnected, and interdependent in the natural world, and how they may give rise to each other as they interrelate to one another. Wikipedia