  The famous Sidorenko's conjecture asserts that for every bipartite graph $H$,
the number of homomorphisms from $H$ to a graph $G$ with given edge density is
minimized when $G$ is pseudorandom. We prove that for any graph $H$, a graph
obtained from replacing edges of $H$ by generalized theta graphs consisting of
even paths satisfies Sidorenko's conjecture, provided a certain divisibility
condition on the number of paths. To achieve this, we prove unconditionally
that bipartite graphs obtained from replacing each edge of a complete graph
with a generalized theta graph satisfy Sidorenko's conjecture, which extends a
result of Conlon, Kim, Lee and Lee [J. Lond. Math. Soc., 2018].
