The Earth’s orbit, and axis tilt, and positions of the summer solstice, etc, have been the same for at least 85M years, if not more. The positions of the continents, which effect ocean currents, have been generally the same for 85M years, and nearly identical to today’s for 34M years. The only thing that has changed is the joining of No America and So America about 6M years ago, if I’m remembering my geology from 55 years ago correctly.
So haw do astronomical forces being on ice ages at periodic intervals, when that is not seen in the record before the current glacial period?
The Solar Cycle (periods where sunspots decrease and increase) has a big effect on climate. Look up the Maunder Minimum and the Little Ice Age.
https://en.m.wikipedia.org/wiki/Maunder_Minimum
The sunspot level is an indirect measure of the strength of the solar magnetic field, which helps shield the Earth from cosmic ray particles.
Cosmic Ray’s hitting the atmosphere create ions and promote cloud formation. More clouds, less sunlight hitting the ground.
The Sun orbits the galaxy, and in parts of the orbit peeks out of the galactic magnetic field.
https://phys.org/news/2019-11-galaxy-magnetic-field.html
Computer Modelling............video games for astrophysiscists.....................