Introduction to Behavior Genetics

Identical twins share the same DNA and are a valuable tool to study genetic influences on behavior because they have the same genes.

Identical twins, even separated at birth, often have similar physical traits and behavior, highlighting the role of genes in behavior.

Adoption studies compare children raised by adoptive parents to those raised by biological parents to understand the influence of genetics and environment on behavior.

Children resemble their biological parents more than their adoptive parents, suggesting a genetic influence on behavior, even when raised in different environments.

Selective breeding involves breeding animals with desired traits to study the inheritance of characteristics and to demonstrate the influence of genes.

The transmission of traits from parents to offspring. It begins at conception when sperm and egg unite, forming a zygote.

The basic unit of heredity that carries genetic information from parents to offspring. They determine traits like physical characteristics and some behaviors.

Twisted strings found in the nucleus of a cell that carry genes. They come in pairs, with 23 pairs making up a human's complete set.

The study that examines the relationship between genetics and behavior. It uses methods such as twin studies and adoption studies to investigate how much of our behavior is influenced by our genes.

Identical twins share the same DNA. Comparing them helps researchers understand how much behavior differences are due to environment, as their genetics are identical.

Researchers study adopted children compared to biological parents and adoptive parents to understand the relative influences of genetics and environment on behavior.

The environment encompasses all external factors that influence development, including family, culture, social interactions, and physical surroundings.

It refers to the interaction between our genetic predispositions and the environmental influences we face. This dynamic interplay shapes who we become.

A technique that uses sound waves to create images of internal organs and tissues, commonly used to monitor fetal development and detect structural abnormalities.

The first two weeks of life immediately after birth, a period of significant adjustment as the infant adapts to life outside the womb.

From two weeks to two years of age, characterized by rapid physical growth and increasing independence, as the baby learns to sit, stand, crawl, walk, and speak.

The period between two and six years of age often referred to as the "questioning stage" due to the child's increasing curiosity. It's also a time of heightened emotional outbursts and temper tantrums.

Between six years of age and puberty, marked by the start of formal schooling and increased socialization with peers. This period is often referred to as the "gang age" and the "smart age."

The period of significant physical changes brought about by the activation of the gonads and the production of sex hormones, typically occurring between ages 8 and 14.

The period after puberty, typically lasting until around 18 years of age, characterized by emotional instability, an identity crisis, and exploration of personal values and beliefs.

Extending from 18 years old to approximately 40, this period involves significant adjustments related to work, marriage, and parenthood, marked by the completion of physical development.

The period between ages 40 and 60, often considered the peak of life's achievements in terms of financial, social, and professional success.

The period starting at age 60 and beyond, marked by physical and mental decline and the cessation of reproductive capabilities.

Identical twins, developed from a single zygote, share the same genes and often exhibit similar physical traits and behavioral tendencies even when raised separately. This suggests that genes play a significant role in influencing these aspects.

Fraternal twins, developed from two separate zygotes, may not have the same genetic makeup and can exhibit different physical traits and behavioral characteristics even when raised together. This highlights the influence of environmental factors.

Adoption studies compare adopted children to their biological parents and adoptive parents to understand the relative contributions of genetics and environment on traits. Children often resemble their biological parents in personality and features even when raised in different environments.

Selective breeding involves choosing animals with specific traits for reproduction to study the influence of genes on inheritance. If a trait can be altered through breeding, it suggests a genetic basis.

The prenatal stage, or gestation period, is the time between conception and birth, lasting approximately 9 months or 280 days. It encompasses three periods: the period of the zygote, the period of the embryo, and the period of the fetus.

This initial period from conception to the end of the second week involves rapid cell division and implantation of the zygote in the uterine wall.

The period from the second week to the third month of pregnancy is characterized by the formation and development of basic organs, including the heart, brain, and intestinal tract.

This stage, spanning from the third month until birth, involves significant growth and development. Major organs begin to function, and the fetus becomes more responsive.

Phenylketonuria (PKU) is an inherited disorder affecting amino-acid metabolism, causing mental retardation. It’s treatable with a special diet if detected early.

Sickle-cell anemia is a disorder caused by abnormally shaped red blood cells, affecting primarily African-American people. Children with this disorder may experience health complications and reduced lifespan.

Tay-Sachs disease is a genetic disorder where the body cannot break down fats, leading to neurological damage and premature death. It commonly affects people of Eastern European Jewish descent.

Down syndrome, caused by an extra chromosome on the 21st pair, results in distinctive physical features and intellectual disability. Individuals with Down syndrome are typically friendly and cheerful.

Turner’s syndrome occurs when females have only one X chromosome on the 23rd pair. Individuals with this disorder have underdeveloped ovaries and may experience intellectual disabilities.

A genetic disorder affecting males, Klinefelter syndrome is caused by an additional X chromosome on the 23rd pair. Individuals with this disorder have underdeveloped testes, female-like breast development and may experience intellectual disabilities.

XYY syndrome, caused by an additional Y chromosome on the 23rd pair, affects males. Individuals with this syndrome are unusually tall and may exhibit aggressive and violent tendencies.