The study on hugs relating to happiness certainly doesn't show personality is
all about environment - the most it can say is that happiness isn't
all about genetics. There's also research showing that things like depression are hereditary - again the most you can say is that there is a genetic influence.
Most people then are inclined to say well it's 50-50, or some combination anyway. This is a theory (not mine) I posted on pandemonium a while back on the same topic which I think is much more plausible than to argue for one or the other, and also more helpful if you're going to talk about nature/nurture wrt some practical or therapuetic sense.
So we are made up of our genes. However, unlike bacteria, human genes cannot be expressed automatically, ie they don't know when and how to express themselves. So they need a signal to tell them when to express themselves in order for development to proceed. In the womb, this is enabled by cell-cell contact, and the unterine environment, and most organs (except the brain and immune system) are fully developed at birth due to this interaction, with specific signals enabling gene expression at critical periods (ie if the genes are NOT stimulated during this period there won't be genetic expression and development in that area will be hindered or not happen at all).
Post-natally, the environment becomes the signal, and most of the development after this time is in the brain, which really determines who we are, and which is nowhere near fully developed at birth. Three factors have to be distinguished - functional potentiality, congenital predisposition, and behaviour, with the environment impacting on the first two to enable behaviour and development. Functional potentiality is a characteristic of the species - it determines whether or not an individual in the species will be able to do specific things, for example humans have the functional potential to speak, since we have brain areas and vocal apparatus that will enable speech, whereas other species do not. Congential predisposition is a characteristic of the individual, something you're born with that will determine whether you're good or bad at something, for example some people have a 'good ear'; they are born with the ability to hear small differences in pitch. But these two factors are useless unless the environment conditions enable them to result in behaviour. For example, a person may be born with functionally fine speech and language systems, and have no congential predispositions that will stop them from speaking, but if they're not exposed to speech from people around them, they will not learn to speak properly, and the longer they are lacking this stimulation, the worse their eventual speaking abilities will be.