People and other species are social creatures whose survival may have been dependent on being part of a group rather than being isolated. Loneliness has been associated with increased inflammation and a reduced resistance to infection by viral diseases. Genetic changes have been found to occur in isolated individuals that lead to the increased inflammatory response in comparison to individuals who have more social support. Our instincts have developed to trust that being part of a group increases our chance of survival. Having a role that fulfills a valued purpose for the group is associated with an increased sense of happiness.
Fitting into groups well can take social skills that need to be nurtured from birth. Infants learn body language at an early age by interacting with a parent who responds to the baby’s cues. If the baby smiles the mother smiles back and the baby learns to smile more readily. If the baby has a mother that doesn’t notice body language though, then the infant may stop smiling as often. Infants and children depend on their caregivers for everything and try to please with their smiles, eye contact, or baby coos. If the infant isn’t receiving eye contact in return however they may stop trying or are scolded they may learn to look away and to avoid eye contact.
Children ideally need emotional support in order to develop trust in themselves and in others. Parents who have limited skills in understanding and accepting their own emotions may not be able to teach their children what they don’t understand themselves. Children who have some role model in their lives who understands emotional skills may cope better than children who don’t.
The topic is discussed in more detail in the book Adult Children of Emotionally Immature Parents: How to Heal from Distant, Rejecting, or Self-Involved Parents, by Lindsay C. Gibson, PsyD, (New Harbinger Pub., Inc., 2015, Oaklnad, CA)  (This book is not a twelve step book and is not affiliated with the Adult Children of Alcoholic or Dysfunctional Parents twelve step group.) An excerpt from page 108:
“Why is emotional connection so crucial?
According to neuroscientist Stephen Porges (2011), mammals have evolved a unique coping instinct in which they are calmed by proximity or engagement with others. Instead of just having the involuntary stress reactions of fight, flight, or freeze, like reptiles do, mammals can calm their heart rate and reduce the physical costs of stress by seeking reassuring contact with others of their kind. Certain vagus nerve pathways in mammals have evolved to allow stress hormones and heart rate to be reduced by confronting in such forms as physical closeness, touch, soothing sounds, and even eye contact. These calming effects conserve valuable energy and also create pleasurable social bonds that promote strong groups.
For all mammals, including humans, something magical happens when this desire to seek comfort switches on. The danger might not go away, but individuals can stay relatively calm as long as they feel tied into their herd, pack, or circle of loved ones. Most mammals have stressful lives, but thanks to their instinct for engaging with others, calming comfort and restored energy are just a friendly contact away. This gives mammals a tremendous advantage over other animals when it comes to dealing with stress in an energy-efficient way, since they don’t have to go into fight, flight, or freeze every time they sense a threat.” 
So a sense of connection to others can help reduce the negative inflammatory effects of the stress response. Some stress can be healthy to help get us moving to meet whatever challenge has occurred. Stress may become more overwhelming however if the person is isolated or never learned social skills or trust enough to ask for help or seek out help. Children in situations with emotionally immature caregivers may learn that people around them can’t be trusted or that trying doesn’t lead to success so why bother trying — they can learn a sense of helplessness and hopelessness rather than finding strength from others.
The book Adult Children of Emotionally Immature Parents: How to Heal from Distant, Rejecting, or Self-Involved Parents, by Lindsay C. Gibson  describes four different types of emotionally immature caregivers, how growing up with them might affect children and how the children might overcome the lessons they learned later in life as adults who only just discovered that emotions aren’t dangerous things to never be discussed or worse that one might be punished for exhibiting. Some emotionally immature people may feel threatened by strong emotions and may react negatively to children who are simply being children. The child in that situation learns to not trust themselves and may not learn that emotions are normal rather than upsetting or frightening.
Severe childhood trauma can lead to changes in the brain that cause ongoing symptoms of Post Traumatic Stress Disorder (PTSD). A new strategy for treating PTSD has been developed which involves electrical stimulation of the vagus nerve called Vagal nerve stimulation (VNS). Which the excerpt from the book  suggests is the nerve pathway that naturally is stimulated when social contact is sought during a stressful situation.
Stress and trauma have been too readily available lately. More police officers were shot today in the U.S. in Baton Rouge, Louisiana. Three are injured, one critically, and three officers were killed Sunday morning. The gunman was a former marine who drove there from his home in Missouri. The gunman was killed at the scene. Further information about his possible motives are not known at this time. Whether there were any accomplices is not known but it is believed he was a lone gunman and there has been no further shooting in the area.
My condolences and best wishes to the families, friends, and coworkers of the slain officers, may they rest in peace, and to the community of Baton Rouge
Emotionally immature parents may raise emotionally immature children who grow up to raise their own emotionally immature children. Help break the trauma cycle by reading the book Adult Children of Emotionally Immature Parents: How to Heal from Distant, Rejecting, or Self-Involved Parents, by Lindsay C. Gibson . Whether you are a parent or a teen or an adult learning more about emotional maturity and immaturity can help understand your own emotions and others. Whatever we grow up with will seem normal to us and as adults we tend to seek out similar relationships to those we were familiar with as children — but sometimes what seems normal to some people isn’t normal for everyone else and there is no need to continue living in abusive situations just because it seemed like a normal part of life as a child.
Lack of emotional skills may increase the risk of acting inappropriately when under severe stress. People need the support of people to help reduce negative effects of stress and increase a sense of connection and purpose. People need to learn emotional skills from people who have emotional skills — or sometimes from a book. 
Disclaimer: Opinions are my own and the information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes.