Due to the inert pair effect, the reluctance of the valence $ns^2$ electrons to participate in bonding increases down the group. In the carbon family (Group 14), the stability of the lower oxidation state ($+2$) increases as we move from lighter to heavier elements, while the stability of the higher oxidation state ($+4$) decreases. Consequently, the most characteristic and stable oxidation state for lead ($\text{Pb}$) is $+2$, whereas for tin ($\text{Sn}$) the $+4$ oxidation state is more stable. Therefore, for lead and tin respectively, the characteristic oxidation states are $+2$ and $+4$.