Look at the siblings

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Giftedness has many faces. We know the mathematical probability of giftedness in an age-matched group, but that doesn’t necessarily result in identifying the specific quantity. Finding gifted individuals takes more than mathematics and understanding that some gifted people hide themselves very well.
Giftedness, whether recognized or not, has a strong impact on a person’s entire life. When we find gifted children, it is worth it to look at their siblings. Although these siblings may be equally gifted, they may also be well-adapted to hiding, and vanish out of our sight. Unrecognized giftedness can significantly impact a person’s life. This is worse still when one child in a family is tested for giftedness and another one is not. The fact that the untested child had “obviously” been unworthy of being tested can torment him throughout his entire life and detrimentally affect his self-esteem.

Many of my counseling sessions revolve around conspicuous second-born children, mostly boys. The first-born, often a girl, is inconspicuous and studious, but not gifted according to parents and teachers.
In counseling, I recommend the testing of each child. Parents often act on this recommendation based on notions of fairness and equality, rather than on necessity. But the results are persuasive.