Everyone stops breathing sometimes, but SIDS babies lack certain hormone that causes reaction (start wiggling to remove pillow or start screaming). IIRC Australian scientists identified the marker recently.

Sort of. Australian scientists discovered there is a correlation between low levels of the enzyme BChE and increased SIDS risk. It's worth noting that there's a fair bit of evidence that actually points to AChE rather than BChE, but AChE is much more volatile and so harder to measure.

It's a particularly interesting finding because we already know that low levels of BChE correspond to an additional challenges waking up from anaesthetic, and the working hypothesis is that this may be linked to the arousal system.

One other potential link is to SUDEP (Sudden Unexpected Death in Epilepsy), which so far we also don't understand the cause of, but it may be similar to SIDS (or in fact, it may even be the exact same condition) - it often presents very similarly (face down in bed, no obvious signs of suffocation, etc.). In fact, in Australia and New Zealand, SIDS is being renamed to SUDI (Sudden Unexpected Death in Infancy), which sort of speaks for itself in terms of similarities.