Each person’s first genuine encounter happens right after birth. The fact that their relationship is created throughout pregnancy, long before conception, is one of the reasons twins are so close (and distinct). Using an ultrasound, this can be noticed as early as 15 weeks after conception.

The twins give each other a full-body hug while still inside the womb, including their arms. A man was observed reaching out to touch the face of a female twin in one particular example of twins. In response, his siblings give him cheek-to-cheek kisses. The twins repeated this behavior a year later by engaging in a similar game of cheek-to-cheek rubbing. This might mean that the twin link is formed when the child is still in the womb and endures long after delivery. In fact, the bond formed in the womb is so strong that twins who have lost one of their children at birth or earlier report experiencing severe emotional pain. According to studies on twin loss, these twins live with profound sensations of emptiness and loneliness.

The twins touch, cuddle, and suck each other when they are put together in the same bed after birth. This approach, known as shared bedding, has been demonstrated to enhance an infant’s heart rate, temperature, respiratory control, number of apneas, need for oxygen, and pace of weight gain. In fact, the well-known example known as “The Saving Hug” is a simple illustration of this. After being placed in the same incubator as his twin, the one of the twins, who was in serious condition, was saved.