  In this study, we performed calculations and analyses of the structure
functions of polarized nucleons and light nuclei, specifically $^3$He and
$^3$H, using second-order Feynman diagrams. Our investigation focused on two
main aspects: Firstly, we examined the symmetry properties of polarized light
sea quarks. Secondly, we conducted a detailed investigation into the impacts of
symmetry breaking on the structure functions of both nucleons and nuclei. To
achieve this, we utilized the existing polarized Parton Distribution Functions
(polarized PDFs) available in the literature. These PDFs were used to calculate
and compare the polarized structure functions $g_1$ and $g_2$ of the nuclei.
Additionally, we examined and analyzed the Bjorken and Efremov-Leader-Teryaev
sum rules by utilizing the moments of the polarized structure functions. The
Lorentz color force components, namely $F_E^{y,n}$ and $F_B^{y,n}$, are
determined using the twist-2, twist-3, and twist-4 matrix elements. When
symmetry breaking is applied, it is observed that they have similar magnitudes
but opposite signs. Our theoretical predictions for the polarized structure
functions of nucleons and light nuclei, taking into account the symmetry
breaking of light sea quarks, exhibit better agreement with experimental data.
