Now Playing: Are genetically-edited babies ethical?

Now Playing: ‘Nutcracker’ babies have us in the Christmas spirit

Now Playing: How fertility companies are taking aim at women in their 20s

Now Playing: American fertility rate hits 30-year low

Now Playing: Texas mom, 38, missing since last week

Now Playing: 1st woman set to officiate an NFL playoff game

Now Playing: Jayme Closs is safe with family after her abduction 3 months ago

Now Playing: Winter storm slams Mid-Atlantic states

Now Playing: Suspect’s car hood pops open during wild high-speed chase

Now Playing: America Strong: Brave little boy’s swift action saves the day

Now Playing: Shooting chaos at a New Jersey mall

Now Playing: Trump blasting Comey and the FBI’s investigation

Now Playing: New details revealed about Jayme Closs’s escape from her captor

Now Playing: Deadly winter storm blankets millions in snow

Now Playing: Mudslides in southern California

Now Playing: Toddler seems unimpressed by new baby brother

Now Playing: Mother and daughter reunite after 52 years

Now Playing: Gunfire sends shoppers running in busy New Jersey mall

Now Playing: Girl, 13, reunited with family after harrowing 88-day ordeal

Now Playing: Major winter storm slams the Midwest