They need love. 
They need touch.
They NEED attention.

But don't take my word for it. 

• "The researchers found DNA methylation differences between "high-contact" children and "low-contact" children at five specific DNA sites, two of which were within genes: one related to the immune system, and one to the metabolic system.
  DNA methylation also acts as a marker for normal biological development and the processes that go along with it, and it can be influenced by external, environmental factors as well.
  Then there was the epigenetic age, the biological aging of blood and tissue. This marker was lower than expected in the kids who hadn't had much contact as babies, and had experienced more distress in their early years, compared with their actual age.
  'In children, we think slower epigenetic aging could reflect less favorable developmental progress," said one of the team, Michael Kobor.'" Science Alert
• "The effects of KMC {kangaroo care} at 1 year on IQ and home environment were still present 20 years later in the most fragile individuals, and KMC parents were more protective and nurturing, reflected by reduced school absenteeism and reduced hyperactivity, aggressiveness, externalization, and socio-deviant conduct of young adults. Neuroimaging showed larger volume of the left caudate nucleus in the KMC group." American Academy of Pediatrics
• "'Kangaroo Care,' skin contact between mother and infant, reduces pain and may reduce crying in response to pain."PubMed
• "Skin-to-skin holding stabilizes heart and respiratory rates, improves oxygen saturation rates, better regulates an infant's body temperature, and conserves a baby's calories." Cleveland Clinic
• "Physical contact and reassurance will make children more secure when they finally head out on their own and make them better able to form their own adult relationships.
  The two gained the spotlight in February when they presented their ideas at the American Association for the Advancement of Science's annual meeting in Philadelphia." Harvard