|

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

Name of the Day

stay connected

highlights

Join BIC on our mission to save handwriting and Fight For Your Write! Writing helps kids become better readers, boosts their confidence and sparks their creativity. Visit BICFightForYourWrite.com to sign our petition to save handwriting!

7 Tips for Reading Aloud to Babies & Toddlers
The AAP advises reading aloud to babies and toddlers because it boosts brain power and has many other benefits. Get some tips for making the most of story time with your tot!

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!

How to Survive Summer Boredom
When the kids are home all day, every day, summer boredom strikes hard and fast. Learn the best summer boredom busters and tips for surviving until September.

12 Birthday Party Favors that Won't Get Thrown Away
The next time you're planning a birthday, forgo the penny candy and cheap toys. Send your guests home with one of these fun and creative party favor ideas!

© 2000-2014 Pearson Education, Inc. All Rights Reserved.