Not necessarily. A child inherits half his genes from each parent, so the leg shape will likely be a mix of the mom's & dad's leg shapes. Some traits are dominant and will show up in most of the children. One can get an idea of how dominant a trait is by looking at his family tree. So, do more than half the relatives in every generation all have bow legs? If so, then the next generation is likely to have them.
Rule out other cause. There may very well be a genetic cause to this but there are also cuases other than heredity that should be considered. After visiting your pmd you may want to consider seeing an orthopaedic surgeon. One in your are can be found at www.Aaos.Org.