Can Baby Walkers, Swingy Swings & Jolly Jumpers cause (or “turn on” genetic predispositions for) Scoliosis in Infants?
From TORTIPELVIS VOL. I, by Dr. Fred Barge: From the womb to birth children begin life with their spine in a “C” curve. The secondary curves are not yet developed as is evident in a newborns inability to hold their head up. 
The secondary curve of the neck develops when the child is placed on their stomach (tummy time) and they start to develop the muscles of the cervical region by lifting their head. This begins the development of the cervical lordotic curve (anterior curve of the neck). 
“Tummy time” is one of the best positions for an infant to develop the arch in its neck and prepare the spinal muscles for upright posture. To develop the secondary low back curve (lumbar arch) babies “creep” or push themselves around on their tummies. The first few months are crucial in the baby’s spine development. There are many products currently on the market (many which have been around for years) that are used to keep babies occupied and safe. However, most of these contraptions inhibit the development of secondary curves. Baby walkers, swings, and jumpers hold the spine in a “C” position and inhibit development of these secondary curves. Some of these products, like the walker, even allow the infant to stand on their feet with erect posture before their spine and pelvis are ready and before the baby’s spine is ready to support the weight of standing upright.
This can lead to early walking and because the lumbar spine has not formed its anterior curve yet, it can also lead to a flattening of the lower back called kyphosis.
Low back kyphosis puts improper pressure on spinal discs and can cause disc wedging and vertebral misalignments (subluxations). The spine can tip to one side and then the other, to compensate, creating a curvature, or scoliosis. Since the child’s spine is still developing, they will adapt to this curve, unless the subluxations and disc wedging are corrected before puberty. While most of these products are useful for busy parents to occupy infants and keep them entertained, time spent in them should be limited and interchanged with greater time spent in “tummy time” and later on creeping and crawling. These are the best possible positions for babies to be in when awake. Many products place emphasis on their ability to allow babies to walk sooner, but because infants may not be physically ready to do so, this can be a unfavorable encouragement. By allowing infants to spend time on their stomachs, they are able to reach milestones like creeping, crawling, cruising, and walking gradually and when their bodies are bio-mechanically prepared to do so. So do swings, jumpers or walkers cause scoliosis in infants? Current thinking is that cases of AIS (adolescent idiopathic scoliosis) are caused by a genetic predisposition to develop scoliosis that is brought out (or turned on) by some external catalyst. The use of these products in infancy is postulated to be one such trigger for scoliosis expression (others include: exposure to specific types of bacteria, trauma, postural stress, nutritional deficiencies, etc…). In all other cases excessive use of these products still has damaging effects. While it will not result in scoliosis for all infants, it may still lead to improper development of some spine contours.