I note that there are no recorded baptisms on SP of any of the children of Alexander St*art and J*an* W*rd*n, so it's not just the twins who are missing.
It looks as if the baptism records, if they ever existed, may not have survived. There could be many reasons for this, for example
- the parents neglected to get them baptised
- the parsh clerk neglected to record the baptism
- they were baptised in a religious denomination whose records have been lost
- they were baptised in a denomination whose records have not been made available to Scotland's People, for example Episcopalian, Methodist, Congregational etc.
The New Statistical Account of St Cyrus
http://www.rootschat.com/links/01tgg/ says that besides adherents of the Established Church (i.e. the Church of Scotland) there were in 1837 23 people who belonged to an Associate congregation in Johnshaven, 3 Bereans and 1 Episcopalian, plus an undefined number who 'do not profess to be in communion with any body of Christians'. Between 1837 and 1845 a family of 11 Seceders (i.e. members of one or other of the Secession churches) had moved into the parish.
The Bereans, in particular, did not practise infant baptism.