The molecular aspect is developed from the studies of the rotational bands in light 4n-nuclei. We show that two rotational bands with K=0+ and 0- such as in 16O* and 20Ne can be unified as the twins with the same molecule-like structure of an alpha particle plus a residual core nucleus. The gap energy betwen two bands is thought from a molecular viewpoint to be the splitting energy of an inversion doublet. The characteristics of the central barrier through which one configuration penetrates into its reflected configuration can be deduced from the properties of the light 4n-nuclei. Experimental splitting energies can be fitted with the reasonable parameters for the central barrier. Some remarks on the properties of the molecule-like structure can further be made.