One twin is always first at something and the other is always
second. One will be taller, lighter, walk first, talk first, say
certain words, and on and on and on. That comment from our
pediatrician was of great solace to my my wife and me.

When twins come into the world parents immediately get focused on
things like weight and height and other measurements. The whole
birth process commands it since twins are often premature. One can
easily get too focused and overly concerned if not for advice like
this. One twin lagging behind in weight does not indicate poor
parenting skills or bad eating habits being picked up - it simply
means that the lighter one is lighter and that is it.

Keeping this in mind will head off many parental reactions for
years to come. In fact some experts encourage more nurturing of the
differences in your twins. It will lead to individuation earlier
and will recognize the two as individuals - something that will
benefit them throughout their life.

The rest of the world will always refer to the kids as "the twins"
even if they don't say it aloud and that can even become a burden
later on. So lay the twin mystique aside as soon as you can,
celebrate the kids as two kids first and remember that one is
always first.