|

How Genes Are Passed On

Through the generations

Through each generation, genes are shuffled and re-shuffled. Half of a baby's genes come from its father and half from its mother. The baby's parents in turn inherited half each of their genes from each of their own parents. One quarter of each person's genes therefore come from the grandparents. So how does this happen? Instead of containing the full complement of 46 chromosomes, each egg and each sperm has just half, or 23, chromosomes each. When they meet at conception the chromosomes pair up to again make up the full complement that now forms the genetic blueprint for the new individual. One of the 23 pairs of chromosomes are sex chromosomes, so gender is also determined at conception. Each egg carries an X chromosome and each sperm either an X or Y. If two X chromosomes combine, the baby will be a girl; if an X and Y chromosome combine, the baby will be a boy (see How gender is determined).

Inheriting genes

Genetic inheritance means that successive generations can share certain characteristics.

excerpted from:

Excerpted from Pregnancy Day by Day.
Copyright © 2009 Dorling Kindersley Limited.
Buy this book now!

Pregnancy Day by Day

Tell us your due date to receive our daily newsletter and find out what is happening in this day of your pregnancy!

Already a member? Log-in here

highlights

Vote Now for the Children's & Teen Choice Book Awards
Voting is open now through May 3 for the Children's and Teen Choice Book Awards — the only national book awards program where the winning author, illustrator, and books of the year are selected by young readers. Encourage your child to vote for his favorites today!

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, and create reading lists for kids!

Top 10 Math & Science Apps for Your Whiz Kid
Looking for the best math and science apps for kids? Check out these cool apps for all ages, which will grow your child's love of the STEM subjects (science, technology, engineering, and math).

Registered for Kindergarten — Now What?
Wondering what to do now that you've signed your child up for kindergarten? Try our award-winning Kindergarten Readiness app! This easy-to-use checklist comes with games and activities to help your child build essential skills for kindergarten. Download the Kindergarten Readiness app today!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

© 2000-2015 Pearson Education, Inc. All Rights Reserved.