  The ''twin birth'' of a positron and an electron by a photon in the presence
of a nucleus, known as Bethe-Heitler pair production, is a key process in
astroparticle physics. The Bethe-Heitler process offers a way of channeling
energy stored in a population of relativistic protons (or nuclei) to
relativistic pairs with extended distributions. Contrary to accelerated
leptons, whose maximum energy is limited by radiative losses, the maximal
energy of pairs is determined by the kinematics of the process and can be as
high as the parent proton energy. We take a closer look at the features of the
injected pair distribution, and provide a novel empirical function that
describes the spectrum of pairs produced by interactions of single-energy
protons with single-energy photons. The function is the kernel of the
Bethe-Heitler pair production spectrum that replaces a double numerical
integration involving the complex differential cross section of the process,
and can be easily implemented in numerical codes. We further examine under
which conditions Bethe-Heitler pairs produced in blazar jets can emit
$\gamma$-ray photons via synchrotron radiation, thus providing an alternative
to the inverse Compton scattering process for high-energy emission in jetted
active galactic nuclei. After taking into consideration the broadband spectral
characteristics of the source, the jet energetics, and the properties of
radiation fields present in the blazar environment, we conclude that
$\gamma$-rays in low- and intermediate-peaked blazars may arise from
Bethe-Heitler pairs in regions of the jet with typical transverse size $\sim
10^{15}$ cm and co-moving magnetic field $5-500$ G.
