Chromosomes Chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells... read more 
are structures within cells that contain DNA DNA Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells... read more and many genes. Genes contain instructions that determine how the body is supposed to look and function.
The sex chromosomes Sex chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells... read more determine whether a fetus becomes male or female. A pair of X and Y chromosomes (XY) results in a male, and a pair of X and X chromosomes (XX) results in a female.
About 1 in every 1,000 boys is born with XYY syndrome. Boys with XYY syndrome tend to be tall and have difficulties with language. The intelligence quotient (IQ) tends to be slightly lower than that of other family members. Learning disabilities Learning Disorders Learning disorders involve an inability to acquire, retain, or broadly use specific skills or information, resulting from deficiencies in attention, memory, or reasoning and affecting academic... read more , attention-deficit/hyperactivity disorder Attention-Deficit/Hyperactivity Disorder (ADHD) Attention-deficit/hyperactivity disorder (ADHD) is poor or short attention span and/or excessive activity and impulsiveness inappropriate for the child’s age that interferes with functioning... read more , and minor behavioral disorders can develop. XYY syndrome was once thought to cause aggressive or violent criminal behavior, but this theory has been disproved.
