When children don't have that bond with their parents or caregivers, the result is a series of negative consequences that may follow them through life. These children are more prone to depression and anxiety, less able to cope with stress and tend to have poor relationships with other people.
There are a number of reasons why children can develop attachment problems. Children in the foster system or who live in orphanages are often moved from caregiver to caregiver, which doesn't give them that important time with a person that they trust. But even children who live with their parents can experience attachment problems. This can happen if the parent is away for periods of time due to a prolonged illness or other life issues. It can also happen if the child is seriously ill and spends a lot of time in hospitals. Behavioral issues in the child may also impact the child/parent bonding process. For example, if the child has a developmental disorder like attention-deficit/hyperactivity disorder (ADHD) or Asperger's syndrome, which is an autism spectrum disorder, these issues can give the child a difficult temperament, which can be trying for parents and impact the bond.
Abuse and neglect are both common offenders that create attachment issues. In situations of neglect, the child's needs for comfort and nurturing weren't met, so they learned not to seek out comfort from other people. And in situations of abuse, these basic needs were met with negative repercussions, discouraging the child from forming attachments with people. The living environment plays a big part as well. The stresses of poverty, single parenthood, marital conflict and family chaos can all contribute to a child's difficulty in forming attachments with others.