Unfortunately there is no blood test for mutancy yet. Maybe in the future. It would make our work so much easier. Until then, unless a child admits their contamination or displays powers beyond those of normal humans, there are only a few guidelines.

Behavioral

Mutant abilities are believed to most often manifest around puberty. It could be earlier or later, but these are some signs to look out for (unfortunately, many of them are also typical characteristics of puberty):

• Suicidal tendancies, suggesting the child knows what they are to become.
• Unusual interest in mutant-related news items, or suspicious disinterest in anything of the sort even when asked.
• Withdrawal from family and/or friends
• Retreat from athletic activities suggesting a fear their abilities or physical mutations may be discovered
• Sudden personality changes
• Disappearing at night
• Having bags packed as though ready to run when discovered
• Change in eating habits (may be psychological or physiological)
• Feelings of overwhelming guilt, shame, self-hatred
• Nightmares
• Outbursts of rage at others
• Feelings of superiority
• Insecurity about showing their body

Physical

Unfortunately physical changes to a body are more likely to be hidden, there are things to watch out for if you get a chance. Depending on your position in relation to the potential mutant, you may be better able to check certain things. Doctors may be able to discover things in a physical, friends might be able to see in the locker room, while parents could inspect younger children during bathtime (not all mutants may manifest at puberty).

• Unusual growths on the skin or body
• Sudden changes in hair, eye, and/or skin coloration, or simply unusual color developing gradually
• Unusual skin texture, scales, rockiness, excessive hairyness
• Higher or lower than normal body temperature
• Enlarged or disproportionate body parts
• Unusual sensitivity or lack of sensitivity to touch, light, or sound

Paranormal

These are usually the strongest signs a person is infected, if they're not obviously different. Some are subtle, some are obvious.

• Objects moving on their own while person is around (especially when angry)
• Glowing auras around all or part of the body (especially when angry)
• Local temperature or weather changing with mood swings
• Immunity or resistance to physical damage