A child genius displays extremely developed intelligence at a very young age, often at only 2 or 3 years old. However, determining what level of intelligence constitutes "genius" and even what intelligence is provokes heated debate among researchers. Determining if your child is a genius requires looking at several different variables and definitions.

Early Signs of Genius

Exceptionally gifted children often demonstrate their intellectual capabilities from a young age. While there are no hard and fast rules, most gifted children tend to display well-developed verbal skills far ahead of their peers. According to the BBC, potential geniuses often start reading at age 2 or 3. They also show mastery of adult vocabulary around the same age, a product of their unusually powerful memories. Not all the signs of genius are verbal, however. Gifted children are also likely to show an awareness of current events, musical talent and a mature sense of humor.

IQ Tests

The closest thing to a scientific measurement of genius in children, according to Duke University's Talent Identification Program, is the intelligence quotient test. Several IQ tests attempt to measure intelligence. Questions differ, but all of the tests measure intelligence in several categories including verbal reasoning, spatial reasoning and active memory. The tests are standardized to produce an average score of 100 with a standard deviation of 15 or 16 points, meaning that about two-thirds of people should score between 85 and 115. Scores above 130 and below 70 are very rare. Gifted children usually score in the top 2 percent of test takers, earning scores above 130. Geniuses usually score higher than 145 or 150 points on these tests, indicating an intelligence level higher than 99.7 percent of the population.

Limitations of IQ Testing

Although IQ tests provide a simple and convenient measurement of intelligence, they have some serious limitations. Exceptionally intelligent children suffering from attention-deficit hyperactivity disorder or other cognitive impairments may underperform on the tests relative to their true intelligence. Some children may achieve genius levels in some categories of intelligence, such as spatial reasoning, but perform normally in other categories. This makes it difficult to sum up their overall intellectual capacity in a single score, according to Cambridge University. Extremely high-performing children are also difficult to differentiate due to a ceiling effect; tests designers don't include many high-difficulty questions, because the vast majority of people would miss them, rendering such questions pointless. Consequently, two children with IQs of 160 and 175, respectively, might both answer every question perfectly and receive the same score even though their abilities differ.

Prodigies and Savants

Not every child deserving of the label "genius" will perform well on IQ tests, according to a 2012 study by Ohio State University. Researchers tested the IQs of eight prodigies, children with exceptional gifts in narrow fields like mathematics, music or art. While the prodigies all scored above the 70th percentile on the overall exam, they actually scored below average in some areas. For example, the prodigies' average score for attentiveness was 8, compared with 8.5 for the control group. These findings suggest the term "genius" is not easily defined by standardized exams, but rather comes in a variety of forms. With no scientific test to decide if a child is an artistic or musical genius, for example, the term genius applied to the arts and humanities requires the subjective judgment of experts. If your child produces brilliant masterpieces on canvas, an art professor is a better judge of his genius than an IQ test.