I know of a similar situation with a mother and her daughters who cry at the slightest emotional stimulation. Sometimes, when they’re together and there is bad news or even a sad scene in a movie, they all break down in tears. Your question about the possibility of a family link is very interesting. It’s widely accepted that psychological disorders, including depression and addictive or manic behaviour, may have a strong genetic link. However, we can’t solely blame genetics, as it’s clear that most emotional disorders only materialise because of environmental factors. So the child of an alcoholic parent – or parents – may carry a gene that predisposes them to the condition, but they will only manifest it if they drink alcohol.
Extensive research links psychological disorders with neurotransmitters in the brain such as serotonin and dopamine. In the same way that power cables have transformers to boost the electrical signal, nerve fibres have junction boxes called synapses that boost electrical impulses through the action of chemicals called neurotransmitters. If you don’t have enough of these chemicals, the nerves can’t function properly. This is the main cause of low moods or depression. Conversely, if the production is too high, it triggers an agitated or manic state. I suspect that the genetic vulnerability is expressed through the under- or over-activity of neurotransmitters.
Crying is the physical expression of a range of different emotions that trigger the tear ducts to produce tears. As well as sad tears – from grief sadness or depression – you can have tears of joy, rage, passion, anger or fear. The crying mechanism is usually an involuntary function – similar to your heart beating or body sweating for example – that is controlled by your subconscious brain. But these automatic responses can be triggered voluntarily, too: think of actors on state going chalky with fear or beetroot red. They are tapping into their personal experiences stored in the subconscious brain and releasing the impulses that trigger these responses.
Breathing is also an involuntary act but we can control it using the conscious brain, such as when we hold our breath. People who meditate regularly develop powers to control their physical responses, so that they can sleep on a bed of nails or walk over hot coals. So I hope you can see that by training your mind, you can control the subconscious or involuntary functions.
In the case of your daughter, at the moment her tears are caused by grief and sadness. She needs to learn a technique for controlling this outpouring by switching emotions. The antidote for sadness is laughter or rate. So I suggest you pass on this advice: whenever you feel you are about to cry, stand in front of a mirror, and fake laughter or rage, whichever is easier. Keep your eyes wide open to note the changes on your face.
The other alternative is to hold your breath. Take a deep breath in and hold it for l5 to 20 seconds. Just when you think you’ll run out of breath, exhale gently and take a shallow half breath in. Hold that for ten seconds. With practice this becomes easily, so don’t panic if it’s hard at first. Holding the breath is also good for controlling hiccups and sneezing. Although it is folk remedial practice, there is now a scientific explanation. Holding your breath retains carbon dioxide in the blood, which is exchanged for oxygen. This results in more oxygen in the brain, which means that the control systems there will work better. Holding your breath also exercises your control over the subconscious brain.
Additionally, I suggest avoiding the consumption of common nerve irritants, such as coffee, alcohol, spicy foods, as well as too much sugar or salt.
Professional therapies such as counselling cognitive therapy, Neurolinguistic programming (NLP) and hypnotherapy are also very useful tools. The earlier the condition is treated, the better the results.